WEBVTT

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have shaped the history of our planet
more<00:01:18.520><c> than</c><00:01:18.680><c> you</c><00:01:18.760><c> might</c><00:01:19.080><c> imagine.</c>

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We<00:01:23.080><c> Earthlings</c><00:01:23.760><c> have</c><00:01:24.160><c> got</c><00:01:24.480><c> used</c><00:01:24.720><c> to</c><00:01:24.800><c> looking</c>

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We Earthlings have got used to looking
 

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We Earthlings have got used to looking
up<00:01:25.360><c> to</c><00:01:25.520><c> an</c><00:01:25.760><c> empty,</c><00:01:26.560><c> inky</c><00:01:26.920><c> expanse</c><00:01:27.480><c> of</c><00:01:27.600><c> night</c>

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up to an empty, inky expanse of night
 

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up to an empty, inky expanse of night
sky,<00:01:28.720><c> adorned</c><00:01:29.240><c> only</c><00:01:29.600><c> by</c><00:01:29.800><c> the</c><00:01:30.000><c> familiar</c>

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sky, adorned only by the familiar
 

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sky, adorned only by the familiar
spattering<00:01:31.240><c> of</c><00:01:31.360><c> the</c><00:01:31.480><c> brightest</c><00:01:31.920><c> stars,</c><00:01:32.840><c> the</c>

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spattering of the brightest stars, the
 

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spattering of the brightest stars, the
subtle<00:01:33.280><c> smudge</c><00:01:33.880><c> of</c><00:01:34.000><c> the</c><00:01:34.080><c> Milky</c><00:01:34.400><c> Way,</c><00:01:35.160><c> and</c><00:01:35.280><c> of</c>

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subtle smudge of the Milky Way, and of
 

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subtle smudge of the Milky Way, and of
course,<00:01:36.280><c> our</c><00:01:36.480><c> lone</c><00:01:36.880><c> moon.</c>

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course, our lone moon.
 

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course, our lone moon.
But<00:01:38.360><c> what</c><00:01:38.520><c> if</c><00:01:38.640><c> our</c><00:01:38.760><c> night</c><00:01:39.000><c> sky</c><00:01:39.280><c> didn't</c><00:01:39.640><c> always</c>

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But what if our night sky didn't always
 

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But what if our night sky didn't always
look<00:01:40.240><c> like</c><00:01:40.400><c> this?</c><00:01:41.120><c> If</c><00:01:41.320><c> Earth</c><00:01:41.600><c> once</c><00:01:42.000><c> had</c><00:01:42.400><c> rings,</c>

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look like this? If Earth once had rings,
 

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look like this? If Earth once had rings,
how<00:01:43.640><c> would</c><00:01:43.840><c> it</c><00:01:44.000><c> have</c><00:01:44.200><c> looked</c><00:01:44.640><c> then?</c>

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how would it have looked then?
 

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how would it have looked then?
To<00:01:46.160><c> really</c><00:01:46.440><c> paint</c><00:01:46.720><c> a</c><00:01:46.760><c> picture</c><00:01:47.080><c> for</c><00:01:47.320><c> you,</c><00:01:47.800><c> let's</c>

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To really paint a picture for you, let's
 

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To really paint a picture for you, let's
imagine<00:01:48.480><c> we're</c><00:01:48.640><c> standing</c><00:01:49.280><c> on</c><00:01:49.440><c> the</c><00:01:49.560><c> surface</c><00:01:50.080><c> of</c>

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imagine we're standing on the surface of
 

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imagine we're standing on the surface of
this<00:01:50.520><c> ancient,</c><00:01:51.240><c> ringed</c><00:01:51.840><c> Earth.</c>

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this ancient, ringed Earth.
 

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this ancient, ringed Earth.
For<00:01:53.200><c> starters,</c><00:01:53.720><c> the</c><00:01:53.840><c> rings</c><00:01:54.240><c> aren't</c><00:01:54.520><c> shiny</c><00:01:54.920><c> and</c>

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For starters, the rings aren't shiny and
 

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For starters, the rings aren't shiny and
bright<00:01:55.320><c> like</c><00:01:55.480><c> Saturn's,</c><00:01:56.320><c> because</c><00:01:56.800><c> we're</c><00:01:57.000><c> too</c>

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bright like Saturn's, because we're too
 

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bright like Saturn's, because we're too
close<00:01:57.640><c> to</c><00:01:57.760><c> the</c><00:01:57.840><c> sun</c><00:01:58.120><c> for</c><00:01:58.280><c> ice</c><00:01:58.440><c> to</c><00:01:58.560><c> persist.</c>

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close to the sun for ice to persist.
 

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close to the sun for ice to persist.
Instead,<00:02:00.760><c> Earth's</c><00:02:01.120><c> rings</c><00:02:01.520><c> are</c><00:02:01.640><c> made</c><00:02:01.920><c> of</c><00:02:02.160><c> rock,</c>

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Instead, Earth's rings are made of rock,
 

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Instead, Earth's rings are made of rock,
rich<00:02:03.360><c> in</c><00:02:03.479><c> silicates</c><00:02:03.796><c> [music]</c>

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rich in silicates [music]
 

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rich in silicates [music]
and<00:02:04.520><c> low</c><00:02:04.760><c> in</c><00:02:04.960><c> iron.</c>

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and low in iron.
 

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and low in iron.
Rocks<00:02:06.280><c> don't</c><00:02:06.520><c> reflect</c><00:02:06.880><c> light,</c><00:02:07.360><c> at</c><00:02:07.479><c> least</c><00:02:07.920><c> not</c>

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Rocks don't reflect light, at least not
 

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Rocks don't reflect light, at least not
efficiently.<00:02:09.119><c> They</c><00:02:09.320><c> absorb</c><00:02:09.880><c> it.</c><00:02:10.360><c> So,</c><00:02:10.520><c> the</c>

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efficiently. They absorb it. So, the
 

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efficiently. They absorb it. So, the
traces<00:02:11.240><c> you</c><00:02:11.360><c> see</c><00:02:11.560><c> overhead</c><00:02:12.160><c> are</c><00:02:12.560><c> pale</c><00:02:13.120><c> and</c>

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traces you see overhead are pale and
 

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traces you see overhead are pale and
dusty.

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dusty.
 

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dusty.
But,<00:02:14.520><c> this</c><00:02:14.680><c> doesn't</c><00:02:14.959><c> make</c><00:02:15.160><c> them</c><00:02:15.440><c> any</c><00:02:15.680><c> less</c>

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But, this doesn't make them any less
 

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But, this doesn't make them any less
dramatic.

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dramatic.
 

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dramatic.
And<00:02:17.560><c> what</c><00:02:17.760><c> you</c><00:02:17.880><c> see</c><00:02:18.080><c> from</c><00:02:18.280><c> the</c><00:02:18.360><c> surface</c><00:02:18.840><c> varies</c>

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And what you see from the surface varies
 

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And what you see from the surface varies
wildly<00:02:20.080><c> depending</c><00:02:20.680><c> on</c><00:02:20.880><c> where</c><00:02:21.120><c> you're</c>

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wildly depending on where you're
 

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wildly depending on where you're
standing.

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standing.
 

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standing.
At<00:02:22.520><c> the</c><00:02:22.640><c> equator,</c><00:02:23.200><c> you</c><00:02:23.520><c> don't</c><00:02:23.840><c> see</c><00:02:24.000><c> a</c><00:02:24.080><c> ring</c><00:02:24.240><c> at</c>

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At the equator, you don't see a ring at
 

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At the equator, you don't see a ring at
all,<00:02:25.040><c> just</c><00:02:25.240><c> a</c><00:02:25.280><c> thin</c><00:02:25.680><c> line</c><00:02:26.040><c> from</c><00:02:26.240><c> one</c><00:02:26.440><c> horizon</c>

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all, just a thin line from one horizon
 

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all, just a thin line from one horizon
to<00:02:27.080><c> the</c><00:02:27.200><c> other.</c>

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to the other.
 

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to the other.
As<00:02:28.320><c> you</c><00:02:28.440><c> move</c><00:02:28.720><c> 20°</c><00:02:29.520><c> from</c><00:02:29.760><c> the</c><00:02:29.880><c> equator</c><00:02:30.360><c> in</c>

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As you move 20° from the equator in
 

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As you move 20° from the equator in
either<00:02:30.920><c> direction,</c><00:02:32.000><c> the</c><00:02:32.120><c> rings</c><00:02:32.360><c> appear</c><00:02:32.840><c> in</c>

01:15.029 --> 01:15.039 align:start position:0%
either direction, the rings appear in
 

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either direction, the rings appear in
their<00:02:33.160><c> full</c><00:02:33.440><c> majesty,</c><00:02:34.440><c> taking</c><00:02:34.800><c> up</c><00:02:35.040><c> a</c>

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their full majesty, taking up a
 

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their full majesty, taking up a
significant<00:02:36.000><c> portion</c><00:02:36.400><c> of</c><00:02:36.480><c> the</c><00:02:36.560><c> sky.</c>

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significant portion of the sky.
 

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significant portion of the sky.
40°<00:02:38.680><c> away,</c><00:02:39.320><c> they</c><00:02:39.480><c> appear</c><00:02:39.840><c> like</c><00:02:40.120><c> an</c><00:02:40.320><c> elongated</c>

01:23.110 --> 01:23.120 align:start position:0%
40° away, they appear like an elongated
 

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40° away, they appear like an elongated
rainbow<00:02:41.560><c> stretching</c><00:02:42.120><c> across</c><00:02:42.600><c> entire</c><00:02:43.240><c> cities.</c>

01:26.630 --> 01:26.640 align:start position:0%
rainbow stretching across entire cities.
 

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rainbow stretching across entire cities.
Here,<00:02:45.240><c> the</c><00:02:45.320><c> bottom</c><00:02:45.640><c> of</c><00:02:45.720><c> the</c><00:02:45.840><c> rings</c><00:02:46.120><c> are</c>

01:28.310 --> 01:28.320 align:start position:0%
Here, the bottom of the rings are
 

01:28.320 --> 01:30.710 align:start position:0%
Here, the bottom of the rings are
blocked<00:02:46.959><c> by</c><00:02:47.080><c> the</c><00:02:47.200><c> curvature</c><00:02:47.680><c> of</c><00:02:47.760><c> the</c><00:02:47.959><c> Earth.</c>

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blocked by the curvature of the Earth.
 

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blocked by the curvature of the Earth.
And<00:02:49.200><c> 90°</c><00:02:49.920><c> away,</c><00:02:50.240><c> at</c><00:02:50.400><c> the</c><00:02:50.480><c> poles,</c><00:02:51.480><c> the</c><00:02:51.640><c> ring</c><00:02:52.200><c> is</c>

01:34.550 --> 01:34.560 align:start position:0%
And 90° away, at the poles, the ring is
 

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And 90° away, at the poles, the ring is
barely<00:02:52.920><c> visible</c><00:02:53.440><c> at</c><00:02:53.680><c> all,</c><00:02:54.360><c> hiding</c><00:02:54.800><c> just</c>

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barely visible at all, hiding just
 

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barely visible at all, hiding just
[music]<00:02:55.160><c> beyond</c><00:02:55.520><c> the</c><00:02:55.600><c> horizon</c><00:02:56.240><c> like</c><00:02:56.600><c> a</c>

01:38.830 --> 01:38.840 align:start position:0%
[music] beyond the horizon like a
 

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[music] beyond the horizon like a
permanent<00:02:57.360><c> twilight.</c>

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permanent twilight.
 

01:41.120 --> 01:42.830 align:start position:0%
permanent twilight.
At<00:02:59.120><c> night,</c><00:02:59.472><c> [music]</c><00:02:59.680><c> things</c><00:03:00.000><c> get</c><00:03:00.360><c> really</c>

01:42.830 --> 01:42.840 align:start position:0%
At night, [music] things get really
 

01:42.840 --> 01:44.070 align:start position:0%
At night, [music] things get really
surreal.

01:44.070 --> 01:44.080 align:start position:0%
surreal.
 

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surreal.
At<00:03:02.080><c> the</c><00:03:02.200><c> equator</c><00:03:02.640><c> and</c><00:03:02.760><c> poles,</c><00:03:03.200><c> not</c><00:03:03.360><c> much</c>

01:45.630 --> 01:45.640 align:start position:0%
At the equator and poles, not much
 

01:45.640 --> 01:48.670 align:start position:0%
At the equator and poles, not much
changes,<00:03:04.600><c> but</c><00:03:04.720><c> in</c><00:03:04.840><c> the</c><00:03:04.959><c> mid-latitudes,</c><00:03:06.280><c> night</c>

01:48.670 --> 01:48.680 align:start position:0%
changes, but in the mid-latitudes, night
 

01:48.680 --> 01:51.910 align:start position:0%
changes, but in the mid-latitudes, night
takes<00:03:06.920><c> on</c><00:03:07.280><c> a</c><00:03:07.440><c> whole</c><00:03:08.080><c> new</c><00:03:08.440><c> meaning.</c>

01:51.910 --> 01:51.920 align:start position:0%
takes on a whole new meaning.
 

01:51.920 --> 01:54.190 align:start position:0%
takes on a whole new meaning.
Dust<00:03:10.160><c> in</c><00:03:10.239><c> the</c><00:03:10.360><c> rings</c><00:03:10.800><c> scatters</c><00:03:11.440><c> daylight</c><00:03:12.000><c> from</c>

01:54.190 --> 01:54.200 align:start position:0%
Dust in the rings scatters daylight from
 

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Dust in the rings scatters daylight from
the<00:03:12.200><c> day</c><00:03:12.440><c> side</c><00:03:12.720><c> of</c><00:03:12.800><c> the</c><00:03:12.880><c> planet</c><00:03:13.320><c> onto</c><00:03:13.600><c> the</c>

01:55.790 --> 01:55.800 align:start position:0%
the day side of the planet onto the
 

01:55.800 --> 01:58.110 align:start position:0%
the day side of the planet onto the
night<00:03:14.040><c> side,</c><00:03:14.760><c> a</c><00:03:14.800><c> phenomenon</c><00:03:15.360><c> known</c><00:03:15.760><c> as</c>

01:58.110 --> 01:58.120 align:start position:0%
night side, a phenomenon known as
 

01:58.120 --> 01:59.550 align:start position:0%
night side, a phenomenon known as
ringshine.

01:59.550 --> 01:59.560 align:start position:0%
ringshine.
 

01:59.560 --> 02:01.510 align:start position:0%
ringshine.
The<00:03:17.519><c> rings</c><00:03:17.880><c> glow</c><00:03:18.160><c> brighter</c><00:03:18.519><c> than</c><00:03:18.680><c> the</c><00:03:18.760><c> moon,</c>

02:01.510 --> 02:01.520 align:start position:0%
The rings glow brighter than the moon,
 

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The rings glow brighter than the moon,
which<00:03:19.720><c> fades</c><00:03:20.120><c> into</c><00:03:20.360><c> obscurity.</c>

02:03.990 --> 02:04.000 align:start position:0%
which fades into obscurity.
 

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which fades into obscurity.
At<00:03:22.080><c> these</c><00:03:22.320><c> latitudes,</c><00:03:23.239><c> darkness</c><00:03:23.760><c> becomes</c><00:03:24.280><c> a</c>

02:06.432 --> 02:06.442 align:start position:0%
At these latitudes, darkness becomes a
 

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At these latitudes, darkness becomes a
[music]<00:03:24.400><c> thing</c><00:03:24.800><c> of</c><00:03:25.000><c> the</c><00:03:25.080><c> past.</c>

02:08.710 --> 02:08.720 align:start position:0%
[music] thing of the past.
 

02:08.720 --> 02:11.550 align:start position:0%
[music] thing of the past.
However,<00:03:27.040><c> you</c><00:03:27.280><c> never</c><00:03:27.640><c> see</c><00:03:27.959><c> the</c><00:03:28.120><c> full</c><00:03:28.440><c> ring.</c>

02:11.550 --> 02:11.560 align:start position:0%
However, you never see the full ring.
 

02:11.560 --> 02:13.710 align:start position:0%
However, you never see the full ring.
As<00:03:29.640><c> much</c><00:03:29.840><c> as</c><00:03:29.959><c> the</c><00:03:30.080><c> sun</c><00:03:30.360><c> traces</c><00:03:30.920><c> an</c><00:03:31.080><c> arc</c><00:03:31.320><c> across</c>

02:13.710 --> 02:13.720 align:start position:0%
As much as the sun traces an arc across
 

02:13.720 --> 02:15.830 align:start position:0%
As much as the sun traces an arc across
the<00:03:31.720><c> sky</c><00:03:32.080><c> in</c><00:03:32.200><c> the</c><00:03:32.320><c> day,</c><00:03:33.160><c> so</c><00:03:33.320><c> the</c><00:03:33.519><c> Earth's</c>

02:15.830 --> 02:15.840 align:start position:0%
the sky in the day, so the Earth's
 

02:15.840 --> 02:18.190 align:start position:0%
the sky in the day, so the Earth's
shadow<00:03:34.120><c> traces</c><00:03:34.519><c> an</c><00:03:34.680><c> arc</c><00:03:34.959><c> across</c><00:03:35.360><c> the</c><00:03:35.480><c> rings</c><00:03:35.959><c> in</c>

02:18.190 --> 02:18.200 align:start position:0%
shadow traces an arc across the rings in
 

02:18.200 --> 02:19.510 align:start position:0%
shadow traces an arc across the rings in
the<00:03:36.152><c> [music]</c><00:03:36.239><c> night.</c>

02:19.510 --> 02:19.520 align:start position:0%
the [music] night.
 

02:19.520 --> 02:20.990 align:start position:0%
the [music] night.
It<00:03:37.560><c> sounds</c><00:03:37.920><c> like</c><00:03:38.160><c> a</c><00:03:38.239><c> world</c><00:03:38.640><c> from</c><00:03:38.840><c> a</c>

02:20.990 --> 02:21.000 align:start position:0%
It sounds like a world from a
 

02:21.000 --> 02:24.710 align:start position:0%
It sounds like a world from a
science-fiction<00:03:39.760><c> novel,</c><00:03:40.560><c> except</c><00:03:41.400><c> it's</c><00:03:41.640><c> not.</c>

02:24.710 --> 02:24.720 align:start position:0%
science-fiction novel, except it's not.
 

02:24.720 --> 02:26.910 align:start position:0%
science-fiction novel, except it's not.
Researchers<00:03:43.239><c> have</c><00:03:43.519><c> actually</c><00:03:44.040><c> found</c><00:03:44.360><c> evidence</c>

02:26.910 --> 02:26.920 align:start position:0%
Researchers have actually found evidence
 

02:26.920 --> 02:29.710 align:start position:0%
Researchers have actually found evidence
that<00:03:45.080><c> Earth</c><00:03:45.480><c> may</c><00:03:45.920><c> have</c><00:03:46.160><c> had</c><00:03:46.400><c> skies</c><00:03:46.920><c> like</c><00:03:47.160><c> this</c>

02:29.710 --> 02:29.720 align:start position:0%
that Earth may have had skies like this
 

02:29.720 --> 02:32.350 align:start position:0%
that Earth may have had skies like this
millions<00:03:48.239><c> of</c><00:03:48.360><c> years</c><00:03:48.600><c> ago.</c>

02:32.350 --> 02:32.360 align:start position:0%
millions of years ago.
 

02:32.360 --> 02:35.070 align:start position:0%
millions of years ago.
Imagine<00:03:50.800><c> what</c><00:03:51.160><c> standing</c><00:03:51.720><c> in</c><00:03:51.840><c> a</c><00:03:51.920><c> ring's</c><00:03:52.400><c> shadow</c>

02:35.070 --> 02:35.080 align:start position:0%
Imagine what standing in a ring's shadow
 

02:35.080 --> 02:37.390 align:start position:0%
Imagine what standing in a ring's shadow
would<00:03:53.200><c> have</c><00:03:53.280><c> been</c><00:03:53.520><c> like.</c><00:03:54.240><c> A</c><00:03:54.320><c> strange</c><00:03:54.680><c> twilight</c>

02:37.390 --> 02:37.400 align:start position:0%
would have been like. A strange twilight
 

02:37.400 --> 02:39.590 align:start position:0%
would have been like. A strange twilight
would<00:03:55.640><c> sweep</c><00:03:56.000><c> across</c><00:03:56.360><c> the</c><00:03:56.600><c> earth,</c><00:03:57.160><c> bringing</c>

02:39.590 --> 02:39.600 align:start position:0%
would sweep across the earth, bringing
 

02:39.600 --> 02:41.150 align:start position:0%
would sweep across the earth, bringing
darkness<00:03:58.160><c> where</c><00:03:58.400><c> there</c><00:03:58.560><c> should</c><00:03:58.720><c> have</c><00:03:58.840><c> been</c>

02:41.150 --> 02:41.160 align:start position:0%
darkness where there should have been
 

02:41.160 --> 02:43.590 align:start position:0%
darkness where there should have been
daylight.<00:04:00.160><c> The</c><00:04:00.240><c> thought</c><00:04:00.520><c> of</c><00:04:00.600><c> it</c><00:04:00.720><c> evokes</c><00:04:01.160><c> the</c>

02:43.590 --> 02:43.600 align:start position:0%
daylight. The thought of it evokes the
 

02:43.600 --> 02:45.910 align:start position:0%
daylight. The thought of it evokes the
similarly<00:04:02.240><c> unforgettable</c><00:04:02.920><c> moments</c><00:04:03.360><c> when</c><00:04:03.600><c> our</c>

02:45.910 --> 02:45.920 align:start position:0%
similarly unforgettable moments when our
 

02:45.920 --> 02:48.070 align:start position:0%
similarly unforgettable moments when our
moon<00:04:04.280><c> blocks</c><00:04:04.600><c> out</c><00:04:04.720><c> the</c><00:04:04.800><c> sun</c><00:04:05.440><c> in</c><00:04:05.560><c> a</c><00:04:05.640><c> solar</c>

02:48.070 --> 02:48.080 align:start position:0%
moon blocks out the sun in a solar
 

02:48.080 --> 02:50.590 align:start position:0%
moon blocks out the sun in a solar
eclipse.<00:04:07.120><c> If</c><00:04:07.240><c> you</c><00:04:07.360><c> need</c><00:04:07.560><c> a</c><00:04:07.600><c> reminder</c><00:04:08.160><c> of</c><00:04:08.240><c> that</c>

02:50.590 --> 02:50.600 align:start position:0%
eclipse. If you need a reminder of that
 

02:50.600 --> 02:53.390 align:start position:0%
eclipse. If you need a reminder of that
particular<00:04:09.240><c> sight,</c><00:04:10.080><c> one</c><00:04:10.480><c> is</c><00:04:10.640><c> coming</c><00:04:11.080><c> on</c>

02:53.390 --> 02:53.400 align:start position:0%
particular sight, one is coming on
 

02:53.400 --> 02:55.910 align:start position:0%
particular sight, one is coming on
August<00:04:11.720><c> 12th</c><00:04:12.120><c> this</c><00:04:12.360><c> year</c><00:04:12.600><c> to</c><00:04:12.760><c> Europe</c><00:04:13.440><c> and</c><00:04:13.600><c> will</c>

02:55.910 --> 02:55.920 align:start position:0%
August 12th this year to Europe and will
 

02:55.920 --> 02:57.870 align:start position:0%
August 12th this year to Europe and will
even<00:04:14.280><c> be</c><00:04:14.440><c> partially</c><00:04:14.920><c> visible</c><00:04:15.320><c> in</c><00:04:15.440><c> parts</c><00:04:15.720><c> of</c>

02:57.870 --> 02:57.880 align:start position:0%
even be partially visible in parts of
 

02:57.880 --> 03:00.149 align:start position:0%
even be partially visible in parts of
America.<00:04:16.959><c> It</c><00:04:17.040><c> promises</c><00:04:17.519><c> to</c><00:04:17.600><c> be</c><00:04:17.880><c> an</c>

02:58.645 --> 03:01.196 align:start position:0%
once appeared in our skies?
If<00:05:15.120><c> you</c><00:05:15.240><c> look</c><00:05:15.600><c> into</c><00:05:16.040><c> the</c><00:05:16.160><c> geological</c><00:05:16.720><c> record,</c>

03:01.196 --> 03:01.206 align:start position:0%
If you look into the geological record,
 

03:01.206 --> 03:03.436 align:start position:0%
If you look into the geological record,
you'll<00:05:17.720><c> notice</c><00:05:18.080><c> something</c><00:05:18.440><c> strange</c><00:05:19.200><c> around</c>

03:03.436 --> 03:03.446 align:start position:0%
you'll notice something strange around
 

03:03.446 --> 03:07.396 align:start position:0%
you'll notice something strange around
the<00:05:19.960><c> 466</c><00:05:21.440><c> million</c><00:05:22.120><c> year</c><00:05:22.360><c> mark.</c><00:05:23.120><c> All</c><00:05:23.320><c> across</c>

03:07.396 --> 03:07.406 align:start position:0%
the 466 million year mark. All across
 

03:07.406 --> 03:09.996 align:start position:0%
the 466 million year mark. All across
the<00:05:23.760><c> globe,</c><00:05:24.440><c> limestone</c><00:05:25.040><c> formations</c><00:05:25.720><c> from</c><00:05:25.960><c> the</c>

03:09.996 --> 03:10.006 align:start position:0%
the globe, limestone formations from the
 

03:10.006 --> 03:13.556 align:start position:0%
the globe, limestone formations from the
Ordovician<00:05:27.040><c> period</c><00:05:27.760><c> show</c><00:05:28.040><c> a</c><00:05:28.160><c> sudden</c><00:05:28.800><c> 100</c><00:05:29.520><c> to</c>

03:13.556 --> 03:13.566 align:start position:0%
Ordovician period show a sudden 100 to
 

03:13.566 --> 03:16.156 align:start position:0%
Ordovician period show a sudden 100 to
1,000-fold<00:05:31.120><c> spike</c><00:05:31.560><c> in</c><00:05:31.760><c> key</c><00:05:32.040><c> elements</c>

03:16.156 --> 03:16.166 align:start position:0%
1,000-fold spike in key elements
 

03:16.166 --> 03:19.236 align:start position:0%
1,000-fold spike in key elements
associated<00:05:33.120><c> with</c><00:05:33.360><c> meteorites,</c><00:05:34.520><c> specifically</c>

03:19.236 --> 03:19.246 align:start position:0%
associated with meteorites, specifically
 

03:19.246 --> 03:21.556 align:start position:0%
associated with meteorites, specifically
L-chondrites.

03:21.556 --> 03:21.566 align:start position:0%
L-chondrites.
 

03:21.566 --> 03:23.276 align:start position:0%
L-chondrites.
For<00:05:37.960><c> decades,</c><00:05:38.720><c> the</c><00:05:38.800><c> prevailing</c><00:05:39.280><c> theory</c>

03:23.276 --> 03:23.286 align:start position:0%
For decades, the prevailing theory
 

03:23.286 --> 03:25.676 align:start position:0%
For decades, the prevailing theory
stated<00:05:39.960><c> that</c><00:05:40.080><c> these</c><00:05:40.440><c> L-chondrite</c><00:05:41.200><c> deposits</c>

03:25.676 --> 03:25.686 align:start position:0%
stated that these L-chondrite deposits
 

03:25.686 --> 03:28.516 align:start position:0%
stated that these L-chondrite deposits
all<00:05:42.240><c> originated</c><00:05:42.840><c> from</c><00:05:43.080><c> one</c><00:05:43.360><c> apparent</c><00:05:43.840><c> body.</c>

03:28.516 --> 03:28.526 align:start position:0%
all originated from one apparent body.
 

03:28.526 --> 03:30.236 align:start position:0%
all originated from one apparent body.
That<00:05:44.960><c> body</c><00:05:45.200><c> broke</c><00:05:45.520><c> apart</c><00:05:45.960><c> somewhere</c><00:05:46.320><c> in</c><00:05:46.440><c> the</c>

03:30.236 --> 03:30.246 align:start position:0%
That body broke apart somewhere in the
 

03:30.246 --> 03:32.316 align:start position:0%
That body broke apart somewhere in the
asteroid<00:05:46.920><c> belt,</c><00:05:47.560><c> scattering</c><00:05:47.808><c> [music]</c><00:05:48.080><c> debris</c>

03:32.316 --> 03:32.326 align:start position:0%
asteroid belt, scattering [music] debris
 

03:32.326 --> 03:34.356 align:start position:0%
asteroid belt, scattering [music] debris
throughout<00:05:49.040><c> the</c><00:05:49.160><c> inner</c><00:05:49.360><c> solar</c><00:05:49.600><c> system.</c><00:05:50.400><c> Some</c>

03:34.356 --> 03:34.366 align:start position:0%
throughout the inner solar system. Some
 

03:34.366 --> 03:36.516 align:start position:0%
throughout the inner solar system. Some
of<00:05:50.720><c> these</c><00:05:50.960><c> fragments</c><00:05:51.440><c> collided</c><00:05:51.960><c> with</c><00:05:52.240><c> Earth,</c>

03:36.516 --> 03:36.526 align:start position:0%
of these fragments collided with Earth,
 

03:36.526 --> 03:38.796 align:start position:0%
of these fragments collided with Earth,
leaving<00:05:53.200><c> impact</c><00:05:53.640><c> craters</c><00:05:54.040><c> dotted</c><00:05:54.560><c> all</c><00:05:54.840><c> over</c>

03:38.796 --> 03:38.806 align:start position:0%
leaving impact craters dotted all over
 

03:38.806 --> 03:40.236 align:start position:0%
leaving impact craters dotted all over
the<00:05:55.160><c> planet.</c>

03:40.236 --> 03:40.246 align:start position:0%
the planet.
 

03:40.246 --> 03:43.076 align:start position:0%
the planet.
But<00:05:56.600><c> in</c><00:05:56.680><c> 2024,</c><00:05:57.960><c> Andy</c><00:05:58.200><c> Tomkins</c><00:05:58.760><c> and</c><00:05:58.880><c> his</c><00:05:59.040><c> team</c>

03:43.076 --> 03:43.086 align:start position:0%
But in 2024, Andy Tomkins and his team
 

03:43.086 --> 03:46.236 align:start position:0%
But in 2024, Andy Tomkins and his team
at<00:05:59.600><c> Monash</c><00:05:59.960><c> University,</c><00:06:00.800><c> Australia,</c><00:06:01.920><c> noticed</c>

03:46.236 --> 03:46.246 align:start position:0%
at Monash University, Australia, noticed
 

03:46.246 --> 03:48.156 align:start position:0%
at Monash University, Australia, noticed
something<00:06:03.000><c> unusual.</c>

03:48.156 --> 03:48.166 align:start position:0%
something unusual.
 

03:48.166 --> 03:51.236 align:start position:0%
something unusual.
They<00:06:04.600><c> analyzed</c><00:06:05.320><c> 21</c><00:06:05.840><c> craters</c><00:06:06.600><c> using</c><00:06:06.960><c> tectonic</c>

03:51.236 --> 03:51.246 align:start position:0%
They analyzed 21 craters using tectonic
 

03:51.246 --> 03:53.196 align:start position:0%
They analyzed 21 craters using tectonic
plate<00:06:07.840><c> reconstruction</c><00:06:08.520><c> models</c><00:06:08.880><c> to</c><00:06:09.000><c> determine</c>

03:53.196 --> 03:53.206 align:start position:0%
plate reconstruction models to determine
 

03:53.206 --> 03:55.636 align:start position:0%
plate reconstruction models to determine
where<00:06:09.840><c> each</c><00:06:10.080><c> impact</c><00:06:10.480><c> site</c><00:06:10.840><c> would</c><00:06:11.000><c> have</c><00:06:11.240><c> been</c>

03:55.636 --> 03:55.646 align:start position:0%
where each impact site would have been
 

03:55.646 --> 03:58.476 align:start position:0%
where each impact site would have been
466<00:06:13.200><c> million</c><00:06:13.560><c> years</c><00:06:13.760><c> ago.</c>

03:58.476 --> 03:58.486 align:start position:0%
466 million years ago.
 

03:58.486 --> 04:00.556 align:start position:0%
466 million years ago.
Accounting<00:06:15.320><c> for</c><00:06:15.600><c> continental</c><00:06:16.200><c> drift</c><00:06:16.640><c> and</c>

04:00.556 --> 04:00.566 align:start position:0%
Accounting for continental drift and
 

04:00.566 --> 04:03.516 align:start position:0%
Accounting for continental drift and
plate<00:06:17.160><c> movement,</c><00:06:18.000><c> the</c><00:06:18.120><c> data</c><00:06:18.600><c> points</c><00:06:19.240><c> started</c>

04:03.516 --> 04:03.526 align:start position:0%
plate movement, the data points started
 

04:03.526 --> 04:05.716 align:start position:0%
plate movement, the data points started
falling<00:06:20.280><c> into</c><00:06:20.520><c> place.</c>

04:05.716 --> 04:05.726 align:start position:0%
falling into place.
 

04:05.726 --> 04:07.916 align:start position:0%
falling into place.
If<00:06:22.120><c> these</c><00:06:22.320><c> impacts</c><00:06:22.720><c> had</c><00:06:22.840><c> come</c><00:06:23.160><c> from</c><00:06:23.520><c> random</c>

04:07.916 --> 04:07.926 align:start position:0%
If these impacts had come from random
 

04:07.926 --> 04:10.156 align:start position:0%
If these impacts had come from random
asteroid<00:06:24.600><c> belt</c><00:06:24.840><c> debris,</c><00:06:25.680><c> we</c><00:06:25.840><c> would</c><00:06:25.960><c> expect</c><00:06:26.360><c> to</c>

04:10.156 --> 04:10.166 align:start position:0%
asteroid belt debris, we would expect to
 

04:10.166 --> 04:12.316 align:start position:0%
asteroid belt debris, we would expect to
see<00:06:26.760><c> a</c><00:06:26.880><c> global</c><00:06:27.520><c> distribution</c><00:06:28.120><c> of</c><00:06:28.240><c> impact</c>

04:12.316 --> 04:12.326 align:start position:0%
see a global distribution of impact
 

04:12.326 --> 04:14.916 align:start position:0%
see a global distribution of impact
sites<00:06:29.000><c> strewn</c><00:06:29.480><c> across</c><00:06:29.840><c> our</c><00:06:30.040><c> planet.</c><00:06:31.080><c> But</c>

04:14.916 --> 04:14.926 align:start position:0%
sites strewn across our planet. But
 

04:14.926 --> 04:16.796 align:start position:0%
sites strewn across our planet. But
Tomkins'<00:06:31.720><c> analysis</c><00:06:32.320><c> revealed</c><00:06:32.720><c> something</c>

04:16.796 --> 04:16.806 align:start position:0%
Tomkins' analysis revealed something
 

04:16.806 --> 04:18.516 align:start position:0%
Tomkins' analysis revealed something
else<00:06:33.280><c> entirely.</c>

04:18.516 --> 04:18.526 align:start position:0%
else entirely.
 

04:18.526 --> 04:21.836 align:start position:0%
else entirely.
All<00:06:34.919><c> 21</c><00:06:35.640><c> impact</c><00:06:36.000><c> sites</c><00:06:36.320><c> fell</c><00:06:36.600><c> within</c><00:06:37.000><c> 30°</c><00:06:38.000><c> of</c>

04:21.836 --> 04:21.846 align:start position:0%
All 21 impact sites fell within 30° of
 

04:21.846 --> 04:23.556 align:start position:0%
All 21 impact sites fell within 30° of
where<00:06:38.280><c> the</c><00:06:38.440><c> equator</c><00:06:39.080><c> would</c><00:06:39.200><c> have</c><00:06:39.320><c> been</c><00:06:39.560><c> back</c>

04:23.556 --> 04:23.566 align:start position:0%
where the equator would have been back
 

04:23.566 --> 04:24.635 align:start position:0%
where the equator would have been back
then.

04:24.635 --> 04:24.645 align:start position:0%
then.
 

04:24.645 --> 04:27.396 align:start position:0%
then.
It<00:06:41.000><c> seemed</c><00:06:41.520><c> too</c><00:06:41.840><c> unlikely</c><00:06:42.480><c> to</c><00:06:42.880><c> just</c><00:06:43.320><c> be</c><00:06:43.560><c> a</c>

04:27.396 --> 04:27.406 align:start position:0%
It seemed too unlikely to just be a
 

04:27.406 --> 04:28.876 align:start position:0%
It seemed too unlikely to just be a
coincidence.

04:28.876 --> 04:28.886 align:start position:0%
coincidence.
 

04:28.886 --> 04:30.516 align:start position:0%
coincidence.
So,<00:06:45.440><c> Tomkins</c><00:06:46.040><c> and</c><00:06:46.120><c> his</c><00:06:46.240><c> team</c><00:06:46.560><c> ran</c><00:06:46.720><c> the</c>

04:30.516 --> 04:30.526 align:start position:0%
So, Tomkins and his team ran the
 

04:30.526 --> 04:31.596 align:start position:0%
So, Tomkins and his team ran the
numbers.

04:31.596 --> 04:31.606 align:start position:0%
numbers.
 

04:31.606 --> 04:34.635 align:start position:0%
numbers.
The<00:06:48.040><c> odds</c><00:06:48.400><c> that</c><00:06:48.840><c> 21</c><00:06:49.520><c> impacts</c><00:06:50.040><c> would</c><00:06:50.280><c> all</c><00:06:50.600><c> land</c>

04:34.635 --> 04:34.645 align:start position:0%
The odds that 21 impacts would all land
 

04:34.645 --> 04:37.956 align:start position:0%
The odds that 21 impacts would all land
within<00:06:51.160><c> that</c><00:06:51.440><c> narrow</c><00:06:52.000><c> equatorial</c><00:06:52.800><c> zone</c><00:06:53.560><c> was</c><00:06:53.800><c> 1</c>

04:37.956 --> 04:37.966 align:start position:0%
within that narrow equatorial zone was 1
 

04:37.966 --> 04:40.396 align:start position:0%
within that narrow equatorial zone was 1
in<00:06:54.440><c> 25</c><00:06:55.440><c> million.</c>

04:40.396 --> 04:40.406 align:start position:0%
in 25 million.
 

04:40.406 --> 04:43.356 align:start position:0%
in 25 million.
As<00:06:56.800><c> I</c><00:06:56.880><c> said,</c><00:06:57.720><c> very</c><00:06:58.120><c> unlikely.</c>

04:43.356 --> 04:43.366 align:start position:0%
As I said, very unlikely.
 

04:43.366 --> 04:45.956 align:start position:0%
As I said, very unlikely.
Still,<00:07:00.280><c> there</c><00:07:00.480><c> could</c><00:07:00.720><c> be</c><00:07:01.040><c> a</c><00:07:01.360><c> non-obvious</c>

04:45.956 --> 04:45.966 align:start position:0%
Still, there could be a non-obvious
 

04:45.966 --> 04:47.556 align:start position:0%
Still, there could be a non-obvious
reason<00:07:02.560><c> for</c><00:07:02.640><c> this</c><00:07:02.800><c> pattern.</c>

04:47.556 --> 04:47.566 align:start position:0%
reason for this pattern.
 

04:47.566 --> 04:49.276 align:start position:0%
reason for this pattern.
To<00:07:03.880><c> be</c><00:07:04.000><c> sure,</c><00:07:04.360><c> the</c><00:07:04.480><c> researchers</c><00:07:05.040><c> compared</c><00:07:05.480><c> the</c>

04:49.276 --> 04:49.286 align:start position:0%
To be sure, the researchers compared the
 

04:49.286 --> 04:51.476 align:start position:0%
To be sure, the researchers compared the
spatial<00:07:06.000><c> clustering</c><00:07:06.560><c> of</c><00:07:06.640><c> these</c><00:07:06.840><c> impacts</c><00:07:07.640><c> to</c>

04:51.476 --> 04:51.486 align:start position:0%
spatial clustering of these impacts to
 

04:51.486 --> 04:54.116 align:start position:0%
spatial clustering of these impacts to
more<00:07:08.080><c> recent</c><00:07:08.520><c> impact</c><00:07:08.960><c> events</c><00:07:09.280><c> on</c><00:07:09.480><c> Earth.</c><00:07:10.280><c> They</c>

04:54.116 --> 04:54.126 align:start position:0%
more recent impact events on Earth. They
 

04:54.126 --> 04:55.716 align:start position:0%
more recent impact events on Earth. They
found<00:07:10.720><c> that</c><00:07:10.800><c> the</c><00:07:10.880><c> modern</c><00:07:11.280><c> impact</c><00:07:11.640><c> craters</c>

04:55.716 --> 04:55.726 align:start position:0%
found that the modern impact craters
 

04:55.726 --> 04:57.836 align:start position:0%
found that the modern impact craters
from<00:07:12.120><c> the</c><00:07:12.200><c> last</c><00:07:12.520><c> 40</c><00:07:12.919><c> million</c><00:07:13.240><c> years</c><00:07:13.800><c> didn't</c>

04:57.836 --> 04:57.846 align:start position:0%
from the last 40 million years didn't
 

04:57.846 --> 04:59.635 align:start position:0%
from the last 40 million years didn't
really<00:07:14.400><c> form</c><00:07:14.720><c> clustered</c><00:07:15.120><c> groups</c><00:07:15.520><c> on</c><00:07:15.680><c> Earth's</c>

04:59.635 --> 04:59.645 align:start position:0%
really form clustered groups on Earth's
 

04:59.645 --> 05:01.756 align:start position:0%
really form clustered groups on Earth's
surface.<00:07:16.919><c> They</c><00:07:17.040><c> followed</c><00:07:17.400><c> the</c><00:07:17.520><c> pattern</c><00:07:17.880><c> you'd</c>

05:01.756 --> 05:01.766 align:start position:0%
surface. They followed the pattern you'd
 

05:01.766 --> 05:03.836 align:start position:0%
surface. They followed the pattern you'd
expect<00:07:18.400><c> for</c><00:07:18.560><c> a</c><00:07:18.640><c> shower</c><00:07:19.160><c> of</c><00:07:19.400><c> random</c><00:07:19.800><c> space</c>

05:03.836 --> 05:03.846 align:start position:0%
expect for a shower of random space
 

05:03.846 --> 05:05.116 align:start position:0%
expect for a shower of random space
debris.

05:05.116 --> 05:05.126 align:start position:0%
debris.
 

05:05.126 --> 05:06.756 align:start position:0%
debris.
But<00:07:21.480><c> the</c><00:07:21.560><c> Ordovician</c><00:07:22.160><c> impacts</c><00:07:22.680><c> were</c><00:07:22.960><c> a</c>

05:06.756 --> 05:06.766 align:start position:0%
But the Ordovician impacts were a
 

05:06.766 --> 05:08.356 align:start position:0%
But the Ordovician impacts were a
different<00:07:23.480><c> story.</c>

05:08.356 --> 05:08.366 align:start position:0%
different story.
 

05:08.366 --> 05:10.956 align:start position:0%
different story.
They<00:07:25.040><c> were</c><00:07:25.200><c> all</c><00:07:25.520><c> clustered</c><00:07:26.040><c> together,</c><00:07:26.800><c> almost</c>

05:10.956 --> 05:10.966 align:start position:0%
They were all clustered together, almost
 

05:10.966 --> 05:12.916 align:start position:0%
They were all clustered together, almost
as<00:07:27.400><c> though</c><00:07:27.720><c> something</c><00:07:28.240><c> had</c><00:07:28.480><c> guided</c><00:07:29.000><c> them</c>

05:12.916 --> 05:12.926 align:start position:0%
as though something had guided them
 

05:12.926 --> 05:13.916 align:start position:0%
as though something had guided them
there.

05:13.916 --> 05:13.926 align:start position:0%
there.
 

05:13.926 --> 05:15.396 align:start position:0%
there.
So,<00:07:30.360><c> how</c><00:07:30.640><c> does</c><00:07:30.800><c> a</c><00:07:30.880><c> rock</c><00:07:31.120><c> shower</c><00:07:31.440><c> from</c><00:07:31.600><c> the</c>

05:15.396 --> 05:15.406 align:start position:0%
So, how does a rock shower from the
 

05:15.406 --> 05:17.556 align:start position:0%
So, how does a rock shower from the
asteroid<00:07:32.120><c> belt</c><00:07:32.360><c> explain</c><00:07:32.960><c> this</c><00:07:33.480><c> crater</c>

05:17.556 --> 05:17.566 align:start position:0%
asteroid belt explain this crater
 

05:17.566 --> 05:19.476 align:start position:0%
asteroid belt explain this crater
pattern<00:07:34.240><c> on</c><00:07:34.440><c> Earth?</c>

05:19.476 --> 05:19.486 align:start position:0%
pattern on Earth?
 

05:19.486 --> 05:21.236 align:start position:0%
pattern on Earth?
To<00:07:35.840><c> answer</c><00:07:36.080><c> this,</c><00:07:36.520><c> scientists</c><00:07:37.040><c> turned</c><00:07:37.360><c> their</c>

05:21.236 --> 05:21.246 align:start position:0%
To answer this, scientists turned their
 

05:21.246 --> 05:23.796 align:start position:0%
To answer this, scientists turned their
attention<00:07:38.000><c> to</c><00:07:38.200><c> our</c><00:07:38.440><c> next-door</c><00:07:38.960><c> neighbors.</c><00:07:39.840><c> If</c>

05:23.796 --> 05:23.806 align:start position:0%
attention to our next-door neighbors. If
 

05:23.806 --> 05:27.036 align:start position:0%
attention to our next-door neighbors. If
this<00:07:40.360><c> was</c><00:07:40.960><c> truly</c><00:07:41.600><c> an</c><00:07:41.760><c> asteroid</c><00:07:42.160><c> belt</c><00:07:42.400><c> breakup,</c>

05:27.036 --> 05:27.046 align:start position:0%
this was truly an asteroid belt breakup,
 

05:27.046 --> 05:29.196 align:start position:0%
this was truly an asteroid belt breakup,
we<00:07:43.480><c> would</c><00:07:43.640><c> find</c><00:07:43.960><c> evidence</c><00:07:44.360><c> all</c><00:07:44.600><c> over</c><00:07:44.760><c> the</c><00:07:44.880><c> moon</c>

05:29.196 --> 05:29.206 align:start position:0%
we would find evidence all over the moon
 

05:29.206 --> 05:30.956 align:start position:0%
we would find evidence all over the moon
and<00:07:45.640><c> Mars,</c><00:07:45.920><c> too.</c>

05:30.956 --> 05:30.966 align:start position:0%
and Mars, too.
 

05:30.966 --> 05:32.916 align:start position:0%
and Mars, too.
Mars<00:07:47.560><c> sits</c><00:07:47.960><c> closer</c><00:07:48.480><c> to</c><00:07:48.560><c> the</c><00:07:48.640><c> asteroid</c><00:07:49.000><c> belt</c>

05:32.916 --> 05:32.926 align:start position:0%
Mars sits closer to the asteroid belt
 

05:32.926 --> 05:35.116 align:start position:0%
Mars sits closer to the asteroid belt
than<00:07:49.280><c> we</c><00:07:49.440><c> do.</c><00:07:50.120><c> Any</c><00:07:50.320><c> fragments</c><00:07:50.880><c> flying</c><00:07:51.200><c> through</c>

05:35.116 --> 05:35.126 align:start position:0%
than we do. Any fragments flying through
 

05:35.126 --> 05:36.956 align:start position:0%
than we do. Any fragments flying through
space<00:07:51.920><c> should</c><00:07:52.200><c> have</c><00:07:52.360><c> collided</c><00:07:52.840><c> with</c><00:07:52.960><c> the</c><00:07:53.040><c> red</c>

05:36.956 --> 05:36.966 align:start position:0%
space should have collided with the red
 

05:36.966 --> 05:38.916 align:start position:0%
space should have collided with the red
planet<00:07:53.600><c> harder</c><00:07:54.080><c> and</c><00:07:54.240><c> more</c><00:07:54.400><c> frequently</c><00:07:55.040><c> than</c>

05:38.916 --> 05:38.926 align:start position:0%
planet harder and more frequently than
 

05:38.926 --> 05:40.516 align:start position:0%
planet harder and more frequently than
they<00:07:55.320><c> did</c><00:07:55.560><c> with</c><00:07:55.800><c> us.</c>

05:40.516 --> 05:40.526 align:start position:0%
they did with us.
 

05:40.526 --> 05:42.316 align:start position:0%
they did with us.
And<00:07:56.880><c> the</c><00:07:56.960><c> surface</c><00:07:57.320><c> of</c><00:07:57.400><c> the</c><00:07:57.480><c> moon,</c><00:07:58.080><c> without</c><00:07:58.480><c> an</c>

05:42.316 --> 05:42.326 align:start position:0%
And the surface of the moon, without an
 

05:42.326 --> 05:44.716 align:start position:0%
And the surface of the moon, without an
atmosphere<00:07:59.080><c> to</c><00:07:59.200><c> protect</c><00:07:59.680><c> it,</c><00:08:00.160><c> is</c><00:08:00.320><c> essentially</c>

05:44.716 --> 05:44.726 align:start position:0%
atmosphere to protect it, is essentially
 

05:44.726 --> 05:46.716 align:start position:0%
atmosphere to protect it, is essentially
a<00:08:01.120><c> permanent</c><00:08:01.800><c> record</c><00:08:02.280><c> of</c><00:08:02.440><c> everything</c><00:08:02.840><c> that's</c>

05:46.716 --> 05:46.726 align:start position:0%
a permanent record of everything that's
 

05:46.726 --> 05:49.396 align:start position:0%
a permanent record of everything that's
ever<00:08:03.200><c> hit</c><00:08:03.360><c> it.</c><00:08:04.120><c> So,</c><00:08:04.640><c> did</c><00:08:04.840><c> this</c><00:08:05.040><c> mysterious</c>

05:49.396 --> 05:49.406 align:start position:0%
ever hit it. So, did this mysterious
 

05:49.406 --> 05:51.916 align:start position:0%
ever hit it. So, did this mysterious
asteroid<00:08:06.160><c> leave</c><00:08:06.440><c> any</c><00:08:06.640><c> clues</c><00:08:07.000><c> behind?</c>

05:51.916 --> 05:51.926 align:start position:0%
asteroid leave any clues behind?
 

05:51.926 --> 05:53.956 align:start position:0%
asteroid leave any clues behind?
That's<00:08:08.360><c> exactly</c><00:08:08.800><c> what</c><00:08:09.160><c> Anthony</c><00:08:09.560><c> Lagain</c><00:08:10.080><c> and</c>

05:53.956 --> 05:53.966 align:start position:0%
That's exactly what Anthony Lagain and
 

05:53.966 --> 05:57.276 align:start position:0%
That's exactly what Anthony Lagain and
his<00:08:10.360><c> team</c><00:08:10.720><c> wanted</c><00:08:11.040><c> to</c><00:08:11.120><c> find</c><00:08:11.400><c> out</c><00:08:11.680><c> in</c><00:08:11.840><c> 2022.</c>

05:57.276 --> 05:57.286 align:start position:0%
his team wanted to find out in 2022.
 

05:57.286 --> 05:59.676 align:start position:0%
his team wanted to find out in 2022.
The<00:08:13.640><c> researchers</c><00:08:14.160><c> examined</c><00:08:14.680><c> 49</c><00:08:15.600><c> large</c>

05:59.676 --> 05:59.686 align:start position:0%
The researchers examined 49 large
 

05:59.686 --> 06:02.996 align:start position:0%
The researchers examined 49 large
craters<00:08:16.360><c> on</c><00:08:16.480><c> Mars,</c><00:08:17.080><c> 45</c><00:08:17.680><c> on</c><00:08:17.880><c> Earth,</c><00:08:18.520><c> and</c><00:08:18.680><c> 91</c><00:08:19.200><c> on</c>

06:02.996 --> 06:03.006 align:start position:0%
craters on Mars, 45 on Earth, and 91 on
 

06:03.006 --> 06:05.076 align:start position:0%
craters on Mars, 45 on Earth, and 91 on
the<00:08:19.360><c> moon</c><00:08:20.080><c> to</c><00:08:20.200><c> determine</c><00:08:20.720><c> if</c><00:08:20.840><c> there</c><00:08:21.000><c> were</c><00:08:21.160><c> any</c>

06:05.076 --> 06:05.086 align:start position:0%
the moon to determine if there were any
 

06:05.086 --> 06:07.516 align:start position:0%
the moon to determine if there were any
spikes<00:08:21.919><c> in</c><00:08:22.160><c> impact</c><00:08:22.600><c> frequency</c><00:08:23.200><c> over</c><00:08:23.400><c> the</c><00:08:23.520><c> last</c>

06:07.516 --> 06:07.526 align:start position:0%
spikes in impact frequency over the last
 

06:07.526 --> 06:09.476 align:start position:0%
spikes in impact frequency over the last
600<00:08:24.320><c> million</c><00:08:24.640><c> years.</c>

06:09.476 --> 06:09.486 align:start position:0%
600 million years.
 

06:09.486 --> 06:12.116 align:start position:0%
600 million years.
Earth,<00:08:26.240><c> as</c><00:08:26.520><c> we</c><00:08:26.800><c> already</c><00:08:27.200><c> saw,</c><00:08:27.680><c> showed</c><00:08:28.040><c> a</c><00:08:28.120><c> jump</c>

06:12.116 --> 06:12.126 align:start position:0%
Earth, as we already saw, showed a jump
 

06:12.126 --> 06:15.516 align:start position:0%
Earth, as we already saw, showed a jump
in<00:08:28.520><c> impacts</c><00:08:29.000><c> about</c><00:08:29.400><c> 460</c><00:08:30.400><c> million</c><00:08:30.720><c> years</c><00:08:30.919><c> ago.</c>

06:15.516 --> 06:15.526 align:start position:0%
in impacts about 460 million years ago.
 

06:15.526 --> 06:18.796 align:start position:0%
in impacts about 460 million years ago.
But<00:08:31.919><c> Mars</c><00:08:32.640><c> and</c><00:08:32.760><c> the</c><00:08:32.840><c> moon</c><00:08:33.640><c> did</c><00:08:33.840><c> not.</c>

06:18.796 --> 06:18.806 align:start position:0%
But Mars and the moon did not.
 

06:18.806 --> 06:20.635 align:start position:0%
But Mars and the moon did not.
Lagain<00:08:35.479><c> thought</c><00:08:35.880><c> this</c><00:08:36.080><c> spike</c><00:08:36.400><c> on</c><00:08:36.560><c> Earth</c><00:08:36.800><c> could</c>

06:20.635 --> 06:20.645 align:start position:0%
Lagain thought this spike on Earth could
 

06:20.645 --> 06:23.195 align:start position:0%
Lagain thought this spike on Earth could
be<00:08:37.120><c> due</c><00:08:37.400><c> to</c><00:08:37.760><c> preservation</c><00:08:38.440><c> bias.</c>

06:23.195 --> 06:23.205 align:start position:0%
be due to preservation bias.
 

06:23.205 --> 06:24.796 align:start position:0%
be due to preservation bias.
The<00:08:39.520><c> craters</c><00:08:40.000><c> in</c><00:08:40.080><c> question</c><00:08:40.599><c> formed</c><00:08:40.960><c> in</c>

06:24.796 --> 06:24.806 align:start position:0%
The craters in question formed in
 

06:24.806 --> 06:26.755 align:start position:0%
The craters in question formed in
tropical<00:08:41.560><c> regions</c><00:08:42.039><c> with</c><00:08:42.320><c> favorable</c>

06:26.755 --> 06:26.765 align:start position:0%
tropical regions with favorable
 

06:26.765 --> 06:28.916 align:start position:0%
tropical regions with favorable
preservation<00:08:43.640><c> conditions,</c><00:08:44.600><c> and</c><00:08:44.800><c> that</c>

06:28.916 --> 06:28.926 align:start position:0%
preservation conditions, and that
 

06:28.926 --> 06:31.036 align:start position:0%
preservation conditions, and that
created<00:08:45.800><c> an</c><00:08:45.880><c> apparent</c><00:08:46.360><c> cluster</c><00:08:46.920><c> around</c>

06:31.036 --> 06:31.046 align:start position:0%
created an apparent cluster around
 

06:31.046 --> 06:32.555 align:start position:0%
created an apparent cluster around
Earth's<00:08:47.600><c> equator.</c>

06:32.555 --> 06:32.565 align:start position:0%
Earth's equator.
 

06:32.565 --> 06:34.956 align:start position:0%
Earth's equator.
He<00:08:49.120><c> argued</c><00:08:49.560><c> that</c><00:08:49.760><c> our</c><00:08:49.920><c> planet</c><00:08:50.320><c> wasn't</c><00:08:50.839><c> pelted</c>

06:34.956 --> 06:34.966 align:start position:0%
He argued that our planet wasn't pelted
 

06:34.966 --> 06:37.876 align:start position:0%
He argued that our planet wasn't pelted
in<00:08:51.360><c> a</c><00:08:51.400><c> thin</c><00:08:51.640><c> belt,</c><00:08:52.360><c> rather</c><00:08:53.120><c> that</c><00:08:53.400><c> only</c><00:08:53.800><c> those</c>

06:37.876 --> 06:37.886 align:start position:0%
in a thin belt, rather that only those
 

06:37.886 --> 06:40.516 align:start position:0%
in a thin belt, rather that only those
impacts<00:08:54.640><c> have</c><00:08:54.760><c> survived</c><00:08:55.240><c> until</c><00:08:55.560><c> now.</c>

06:40.516 --> 06:40.526 align:start position:0%
impacts have survived until now.
 

06:40.526 --> 06:42.716 align:start position:0%
impacts have survived until now.
But<00:08:57.000><c> Tompkins</c><00:08:57.480><c> had</c><00:08:57.600><c> a</c><00:08:57.640><c> different</c><00:08:58.000><c> idea.</c>

06:42.716 --> 06:42.726 align:start position:0%
But Tompkins had a different idea.
 

06:42.726 --> 06:44.516 align:start position:0%
But Tompkins had a different idea.
What<00:08:59.320><c> if</c><00:08:59.560><c> the</c><00:08:59.680><c> asteroid</c><00:09:00.240><c> that</c><00:09:00.360><c> caused</c><00:09:00.720><c> the</c>

06:44.516 --> 06:44.526 align:start position:0%
What if the asteroid that caused the
 

06:44.526 --> 06:47.076 align:start position:0%
What if the asteroid that caused the
Ordovician<00:09:01.440><c> meteor</c><00:09:01.880><c> shower</c><00:09:02.560><c> didn't</c><00:09:02.880><c> break</c><00:09:03.200><c> up</c>

06:47.076 --> 06:47.086 align:start position:0%
Ordovician meteor shower didn't break up
 

06:47.086 --> 06:49.992 align:start position:0%
Ordovician meteor shower didn't break up
in<00:09:03.440><c> the</c><00:09:03.520><c> asteroid</c><00:09:03.920><c> belt,</c><00:09:04.560><c> but</c><00:09:04.960><c> right</c><00:09:05.360><c> here</c><00:09:06.120><c> in</c>

06:49.992 --> 06:50.002 align:start position:0%
in the asteroid belt, but right here in
 

06:50.002 --> 06:52.356 align:start position:0%
in the asteroid belt, but right here in
[music]<00:09:06.400><c> Earth's</c><00:09:06.839><c> orbital</c><00:09:07.280><c> space?</c>

06:52.356 --> 06:52.366 align:start position:0%
[music] Earth's orbital space?
 

06:52.366 --> 06:54.796 align:start position:0%
[music] Earth's orbital space?
What<00:09:08.839><c> if</c><00:09:09.080><c> a</c><00:09:09.200><c> massive</c><00:09:09.839><c> asteroid</c><00:09:10.400><c> passed</c><00:09:10.760><c> close</c>

06:54.796 --> 06:54.806 align:start position:0%
What if a massive asteroid passed close
 

06:54.806 --> 06:56.396 align:start position:0%
What if a massive asteroid passed close
enough<00:09:11.280><c> to</c><00:09:11.440><c> Earth</c><00:09:11.680><c> that</c><00:09:11.920><c> our</c><00:09:12.120><c> planet's</c>

06:56.396 --> 06:56.406 align:start position:0%
enough to Earth that our planet's
 

06:56.406 --> 06:59.596 align:start position:0%
enough to Earth that our planet's
gravity<00:09:13.200><c> tore</c><00:09:13.800><c> it</c><00:09:14.040><c> apart?</c><00:09:15.240><c> And</c><00:09:15.360><c> what</c><00:09:15.520><c> if</c><00:09:15.640><c> those</c>

06:59.596 --> 06:59.606 align:start position:0%
gravity tore it apart? And what if those
 

06:59.606 --> 07:01.356 align:start position:0%
gravity tore it apart? And what if those
fragments<00:09:16.480><c> didn't</c><00:09:16.720><c> scatter</c><00:09:17.160><c> across</c><00:09:17.520><c> the</c>

07:01.356 --> 07:01.366 align:start position:0%
fragments didn't scatter across the
 

07:01.366 --> 07:03.876 align:start position:0%
fragments didn't scatter across the
inner<00:09:17.839><c> solar</c><00:09:18.160><c> system,</c><00:09:19.040><c> but</c><00:09:19.200><c> stayed</c><00:09:19.760><c> right</c>

07:03.876 --> 07:03.886 align:start position:0%
inner solar system, but stayed right
 

07:03.886 --> 07:05.916 align:start position:0%
inner solar system, but stayed right
here<00:09:20.839><c> in</c><00:09:21.040><c> orbit?</c>

07:05.916 --> 07:05.926 align:start position:0%
here in orbit?
 

07:05.926 --> 07:09.516 align:start position:0%
here in orbit?
What<00:09:22.520><c> if</c><00:09:23.200><c> 460</c><00:09:24.280><c> million</c><00:09:24.640><c> years</c><00:09:24.839><c> ago</c>

07:09.516 --> 07:09.526 align:start position:0%
What if 460 million years ago
 

07:09.526 --> 07:13.156 align:start position:0%
What if 460 million years ago
Earth<00:09:26.280><c> had</c><00:09:26.880><c> rings?</c>

07:13.156 --> 07:13.166 align:start position:0%
Earth had rings?
 

07:13.166 --> 07:15.516 align:start position:0%
Earth had rings?
When<00:09:29.600><c> you</c><00:09:29.720><c> think</c><00:09:30.080><c> of</c><00:09:30.200><c> rings,</c><00:09:30.560><c> your</c><00:09:30.839><c> mind</c><00:09:31.320><c> jumps</c>

07:15.516 --> 07:15.526 align:start position:0%
When you think of rings, your mind jumps
 

07:15.526 --> 07:18.836 align:start position:0%
When you think of rings, your mind jumps
to<00:09:31.920><c> Saturn,</c><00:09:32.720><c> the</c><00:09:32.920><c> iconic</c><00:09:33.800><c> illuminated</c><00:09:34.640><c> arcs</c>

07:18.836 --> 07:18.846 align:start position:0%
to Saturn, the iconic illuminated arcs
 

07:18.846 --> 07:21.756 align:start position:0%
to Saturn, the iconic illuminated arcs
circling<00:09:35.920><c> the</c><00:09:36.040><c> queen</c><00:09:36.600><c> of</c><00:09:36.760><c> the</c><00:09:36.839><c> solar</c><00:09:37.120><c> system.</c>

07:21.756 --> 07:21.766 align:start position:0%
circling the queen of the solar system.
 

07:21.766 --> 07:25.116 align:start position:0%
circling the queen of the solar system.
And<00:09:38.360><c> though</c><00:09:38.600><c> not</c><00:09:39.040><c> as</c><00:09:39.320><c> epic,</c><00:09:40.400><c> all</c><00:09:40.760><c> four</c><00:09:41.120><c> gas</c>

07:25.116 --> 07:25.126 align:start position:0%
And though not as epic, all four gas
 

07:25.126 --> 07:27.596 align:start position:0%
And though not as epic, all four gas
giants<00:09:41.800><c> have</c><00:09:42.160><c> rings</c><00:09:42.480><c> of</c><00:09:42.560><c> their</c><00:09:42.800><c> own.</c>

07:27.596 --> 07:27.606 align:start position:0%
giants have rings of their own.
 

07:27.606 --> 07:30.156 align:start position:0%
giants have rings of their own.
But,<00:09:44.360><c> as</c><00:09:44.520><c> it</c><00:09:44.640><c> turns</c><00:09:44.960><c> out,</c><00:09:45.480><c> rocky</c><00:09:45.920><c> planets</c><00:09:46.280><c> can</c>

07:30.156 --> 07:30.166 align:start position:0%
But, as it turns out, rocky planets can
 

07:30.166 --> 07:32.476 align:start position:0%
But, as it turns out, rocky planets can
have<00:09:46.800><c> rings,</c><00:09:46.886><c> [music]</c><00:09:47.200><c> too.</c><00:09:48.000><c> They</c><00:09:48.120><c> just</c><00:09:48.360><c> don't</c>

07:32.476 --> 07:32.486 align:start position:0%
have rings, [music] too. They just don't
 

07:32.486 --> 07:34.836 align:start position:0%
have rings, [music] too. They just don't
last<00:09:49.200><c> as</c><00:09:49.360><c> long</c><00:09:49.720><c> for</c><00:09:50.040><c> various</c><00:09:50.560><c> reasons</c><00:09:50.960><c> we'll</c>

07:34.836 --> 07:34.846 align:start position:0%
last as long for various reasons we'll
 

07:34.846 --> 07:36.396 align:start position:0%
last as long for various reasons we'll
discuss<00:09:51.480><c> later.</c>

07:36.396 --> 07:36.406 align:start position:0%
discuss later.
 

07:36.406 --> 07:38.196 align:start position:0%
discuss later.
Before<00:09:53.000><c> we</c><00:09:53.080><c> get</c><00:09:53.240><c> to</c><00:09:53.360><c> all</c><00:09:53.480><c> that,</c><00:09:54.080><c> we</c><00:09:54.200><c> need</c><00:09:54.360><c> to</c>

07:38.196 --> 07:38.206 align:start position:0%
Before we get to all that, we need to
 

07:38.206 --> 07:40.356 align:start position:0%
Before we get to all that, we need to
work<00:09:54.720><c> out</c><00:09:54.960><c> how</c><00:09:55.520><c> an</c><00:09:55.720><c> asteroid</c><00:09:56.240><c> could</c>

07:40.356 --> 07:40.366 align:start position:0%
work out how an asteroid could
 

07:40.366 --> 07:43.676 align:start position:0%
work out how an asteroid could
spontaneously<00:09:57.520><c> fracture</c><00:09:58.000><c> above</c><00:09:58.360><c> Earth</c><00:09:58.760><c> 466</c>

07:43.676 --> 07:43.686 align:start position:0%
spontaneously fracture above Earth 466
 

07:43.686 --> 07:45.316 align:start position:0%
spontaneously fracture above Earth 466
million<00:10:00.320><c> years</c><00:10:00.520><c> ago.</c>

07:45.316 --> 07:45.326 align:start position:0%
million years ago.
 

07:45.326 --> 07:47.236 align:start position:0%
million years ago.
As<00:10:01.880><c> an</c><00:10:02.080><c> asteroid</c><00:10:02.600><c> gets</c><00:10:02.880><c> closer</c><00:10:03.240><c> to</c><00:10:03.360><c> our</c>

07:47.236 --> 07:47.246 align:start position:0%
As an asteroid gets closer to our
 

07:47.246 --> 07:48.916 align:start position:0%
As an asteroid gets closer to our
planet,<00:10:04.160><c> the</c><00:10:04.280><c> side</c><00:10:04.571><c> [music]</c><00:10:04.640><c> facing</c><00:10:05.120><c> the</c>

07:48.916 --> 07:48.926 align:start position:0%
planet, the side [music] facing the
 

07:48.926 --> 07:51.076 align:start position:0%
planet, the side [music] facing the
planet<00:10:05.680><c> experiences</c><00:10:06.600><c> a</c><00:10:06.680><c> stronger</c>

07:51.076 --> 07:51.086 align:start position:0%
planet experiences a stronger
 

07:51.086 --> 07:53.116 align:start position:0%
planet experiences a stronger
gravitational<00:10:08.040><c> pull</c><00:10:08.360><c> than</c><00:10:08.480><c> the</c><00:10:08.560><c> side</c><00:10:08.960><c> facing</c>

07:53.116 --> 07:53.126 align:start position:0%
gravitational pull than the side facing
 

07:53.126 --> 07:55.876 align:start position:0%
gravitational pull than the side facing
away<00:10:09.720><c> from</c><00:10:09.960><c> it.</c><00:10:10.680><c> This</c><00:10:10.920><c> difference</c><00:10:11.560><c> is</c><00:10:11.760><c> called</c>

07:55.876 --> 07:55.886 align:start position:0%
away from it. This difference is called
 

07:55.886 --> 07:58.276 align:start position:0%
away from it. This difference is called
the<00:10:12.280><c> tidal</c><00:10:12.760><c> force,</c><00:10:13.600><c> the</c><00:10:13.720><c> same</c><00:10:14.080><c> phenomenon</c>

07:58.276 --> 07:58.286 align:start position:0%
the tidal force, the same phenomenon
 

07:58.286 --> 08:00.476 align:start position:0%
the tidal force, the same phenomenon
that<00:10:14.720><c> causes</c><00:10:15.160><c> the</c><00:10:15.240><c> moon</c><00:10:15.880><c> to</c><00:10:16.040><c> raise</c><00:10:16.360><c> ocean</c>

08:00.476 --> 08:00.486 align:start position:0%
that causes the moon to raise ocean
 

08:00.486 --> 08:02.556 align:start position:0%
that causes the moon to raise ocean
tides<00:10:17.200><c> on</c><00:10:17.320><c> our</c><00:10:17.440><c> shore.</c>

08:02.556 --> 08:02.566 align:start position:0%
tides on our shore.
 

08:02.566 --> 08:04.436 align:start position:0%
tides on our shore.
For<00:10:19.000><c> most</c><00:10:19.320><c> objects,</c><00:10:19.720><c> their</c><00:10:19.960><c> internal</c><00:10:20.360><c> gravity</c>

08:04.436 --> 08:04.446 align:start position:0%
For most objects, their internal gravity
 

08:04.446 --> 08:06.796 align:start position:0%
For most objects, their internal gravity
is<00:10:20.880><c> strong</c><00:10:21.240><c> enough</c><00:10:21.480><c> to</c><00:10:21.600><c> hold</c><00:10:21.880><c> them</c><00:10:22.000><c> together.</c>

08:06.796 --> 08:06.806 align:start position:0%
is strong enough to hold them together.
 

08:06.806 --> 08:08.836 align:start position:0%
is strong enough to hold them together.
But,<00:10:23.240><c> the</c><00:10:23.320><c> closer</c><00:10:23.880><c> to</c><00:10:24.000><c> the</c><00:10:24.080><c> planet</c><00:10:24.400><c> they</c><00:10:24.520><c> get,</c>

08:08.836 --> 08:08.846 align:start position:0%
But, the closer to the planet they get,
 

08:08.846 --> 08:11.676 align:start position:0%
But, the closer to the planet they get,
the<00:10:25.240><c> stronger</c><00:10:25.920><c> the</c><00:10:26.040><c> tidal</c><00:10:26.400><c> forces</c><00:10:26.800><c> grow.</c>

08:11.676 --> 08:11.686 align:start position:0%
the stronger the tidal forces grow.
 

08:11.686 --> 08:14.156 align:start position:0%
the stronger the tidal forces grow.
If<00:10:28.160><c> the</c><00:10:28.280><c> orbiting</c><00:10:28.680><c> object</c><00:10:29.000><c> gets</c><00:10:29.240><c> too</c><00:10:29.400><c> close,</c>

08:14.156 --> 08:14.166 align:start position:0%
If the orbiting object gets too close,
 

08:14.166 --> 08:15.636 align:start position:0%
If the orbiting object gets too close,
there<00:10:30.600><c> comes</c><00:10:30.880><c> a</c><00:10:30.920><c> point</c><00:10:31.280><c> when</c><00:10:31.440><c> the</c><00:10:31.520><c> tidal</c>

08:15.636 --> 08:15.646 align:start position:0%
there comes a point when the tidal
 

08:15.646 --> 08:18.076 align:start position:0%
there comes a point when the tidal
forces<00:10:32.320><c> of</c><00:10:32.400><c> the</c><00:10:32.520><c> planet</c><00:10:32.920><c> eventually</c><00:10:34.000><c> rip</c><00:10:34.240><c> it</c>

08:18.076 --> 08:18.086 align:start position:0%
forces of the planet eventually rip it
 

08:18.086 --> 08:19.436 align:start position:0%
forces of the planet eventually rip it
apart.

08:19.436 --> 08:19.446 align:start position:0%
apart.
 

08:19.446 --> 08:21.796 align:start position:0%
apart.
The<00:10:35.880><c> distance</c><00:10:36.440><c> at</c><00:10:36.640><c> which</c><00:10:36.880><c> this</c><00:10:37.120><c> happens</c><00:10:37.880><c> is</c>

08:21.796 --> 08:21.806 align:start position:0%
The distance at which this happens is
 

08:21.806 --> 08:24.916 align:start position:0%
The distance at which this happens is
called<00:10:38.360><c> the</c><00:10:38.480><c> Roche</c><00:10:38.880><c> limit.</c><00:10:39.839><c> It</c><00:10:40.080><c> isn't</c><00:10:40.400><c> a</c><00:10:40.600><c> hard</c>

08:24.916 --> 08:24.926 align:start position:0%
called the Roche limit. It isn't a hard
 

08:24.926 --> 08:27.036 align:start position:0%
called the Roche limit. It isn't a hard
and<00:10:41.400><c> fast</c><00:10:41.760><c> distance,</c><00:10:42.440><c> since</c><00:10:42.720><c> it</c><00:10:42.839><c> varies</c>

08:27.036 --> 08:27.046 align:start position:0%
and fast distance, since it varies
 

08:27.046 --> 08:29.236 align:start position:0%
and fast distance, since it varies
depending<00:10:43.800><c> on</c><00:10:43.920><c> a</c><00:10:43.960><c> few</c><00:10:44.200><c> things,</c><00:10:44.960><c> namely</c><00:10:45.400><c> the</c>

08:29.236 --> 08:29.246 align:start position:0%
depending on a few things, namely the
 

08:29.246 --> 08:31.156 align:start position:0%
depending on a few things, namely the
planet's<00:10:45.920><c> mass</c><00:10:46.240><c> and</c><00:10:46.360><c> radius,</c><00:10:47.160><c> and</c><00:10:47.280><c> the</c>

08:31.156 --> 08:31.166 align:start position:0%
planet's mass and radius, and the
 

08:31.166 --> 08:33.555 align:start position:0%
planet's mass and radius, and the
object's<00:10:47.920><c> density</c><00:10:48.360><c> and</c><00:10:48.480><c> composition.</c><00:10:49.720><c> For</c>

08:33.555 --> 08:33.565 align:start position:0%
object's density and composition. For
 

08:33.565 --> 08:36.236 align:start position:0%
object's density and composition. For
example,<00:10:50.400><c> the</c><00:10:50.720><c> Earth's</c><00:10:51.320><c> Roche</c><00:10:51.640><c> limit</c><00:10:52.160><c> for</c><00:10:52.400><c> a</c>

08:36.236 --> 08:36.246 align:start position:0%
example, the Earth's Roche limit for a
 

08:36.246 --> 08:39.036 align:start position:0%
example, the Earth's Roche limit for a
rigid<00:10:52.960><c> body</c><00:10:53.240><c> made</c><00:10:53.560><c> of</c><00:10:53.760><c> solid</c><00:10:54.240><c> rock,</c><00:10:54.839><c> like</c><00:10:55.080><c> the</c>

08:39.036 --> 08:39.046 align:start position:0%
rigid body made of solid rock, like the
 

08:39.046 --> 08:41.116 align:start position:0%
rigid body made of solid rock, like the
Ordovician<00:10:56.000><c> L</c><00:10:56.280><c> chondrite</c><00:10:56.839><c> asteroid</c><00:10:57.240><c> we've</c>

08:41.116 --> 08:41.126 align:start position:0%
Ordovician L chondrite asteroid we've
 

08:41.126 --> 08:44.916 align:start position:0%
Ordovician L chondrite asteroid we've
been<00:10:57.520><c> talking</c><00:10:57.960><c> about,</c><00:10:58.720><c> is</c><00:10:58.920><c> about</c><00:10:59.360><c> 3,100</c><00:11:00.720><c> km</c>

08:44.916 --> 08:44.926 align:start position:0%
been talking about, is about 3,100 km
 

08:44.926 --> 08:47.196 align:start position:0%
been talking about, is about 3,100 km
above<00:11:01.640><c> the</c><00:11:01.760><c> surface</c><00:11:02.160><c> of</c><00:11:02.280><c> the</c><00:11:02.360><c> planet.</c>

08:47.196 --> 08:47.206 align:start position:0%
above the surface of the planet.
 

08:47.206 --> 08:48.876 align:start position:0%
above the surface of the planet.
For<00:11:03.640><c> a</c><00:11:03.680><c> pile</c><00:11:04.040><c> of</c><00:11:04.200><c> rubble</c><00:11:04.560><c> loosely</c><00:11:05.000><c> held</c>

08:48.876 --> 08:48.886 align:start position:0%
For a pile of rubble loosely held
 

08:48.886 --> 08:53.036 align:start position:0%
For a pile of rubble loosely held
together<00:11:05.480><c> by</c><00:11:05.640><c> gravity,</c><00:11:06.680><c> it</c><00:11:06.920><c> is</c><00:11:07.280><c> about</c><00:11:07.720><c> 15,800</c>

08:53.036 --> 08:53.046 align:start position:0%
together by gravity, it is about 15,800
 

08:53.046 --> 08:54.996 align:start position:0%
together by gravity, it is about 15,800
km<00:11:09.760><c> above</c><00:11:10.000><c> the</c><00:11:10.120><c> surface.</c>

08:54.996 --> 08:55.006 align:start position:0%
km above the surface.
 

08:55.006 --> 08:57.636 align:start position:0%
km above the surface.
So,<00:11:12.120><c> fairly</c><00:11:12.600><c> possible.</c>

08:57.636 --> 08:57.646 align:start position:0%
So, fairly possible.
 

08:57.646 --> 08:59.156 align:start position:0%
So, fairly possible.
Next,<00:11:14.280><c> we</c><00:11:14.360><c> need</c><00:11:14.520><c> to</c><00:11:14.640><c> know</c><00:11:14.800><c> what</c><00:11:15.000><c> happens</c><00:11:15.320><c> to</c>

08:59.156 --> 08:59.166 align:start position:0%
Next, we need to know what happens to
 

08:59.166 --> 09:01.356 align:start position:0%
Next, we need to know what happens to
the<00:11:15.560><c> fragments</c><00:11:16.240><c> once</c><00:11:16.480><c> this</c><00:11:16.920><c> near-Earth</c>

09:01.356 --> 09:01.366 align:start position:0%
the fragments once this near-Earth
 

09:01.366 --> 09:03.956 align:start position:0%
the fragments once this near-Earth
asteroid<00:11:18.080><c> breaks</c><00:11:18.440><c> up.</c><00:11:19.200><c> How</c><00:11:19.400><c> do</c><00:11:19.520><c> they</c><00:11:19.720><c> end</c><00:11:20.000><c> up</c>

09:03.956 --> 09:03.966 align:start position:0%
asteroid breaks up. How do they end up
 

09:03.966 --> 09:06.476 align:start position:0%
asteroid breaks up. How do they end up
in<00:11:20.440><c> a</c><00:11:20.560><c> neat</c><00:11:21.120><c> circular</c><00:11:21.760><c> orbit</c><00:11:22.160><c> around</c><00:11:22.640><c> the</c>

09:06.476 --> 09:06.486 align:start position:0%
in a neat circular orbit around the
 

09:06.486 --> 09:07.916 align:start position:0%
in a neat circular orbit around the
equator?

09:07.916 --> 09:07.926 align:start position:0%
equator?
 

09:07.926 --> 09:10.396 align:start position:0%
equator?
Well,<00:11:25.040><c> when</c><00:11:25.200><c> the</c><00:11:25.320><c> asteroid</c><00:11:25.720><c> breaks</c><00:11:25.960><c> apart,</c>

09:10.396 --> 09:10.406 align:start position:0%
Well, when the asteroid breaks apart,
 

09:10.406 --> 09:13.116 align:start position:0%
Well, when the asteroid breaks apart,
its<00:11:26.920><c> total</c><00:11:27.400><c> momentum</c><00:11:28.000><c> is</c><00:11:28.200><c> conserved</c><00:11:29.000><c> among</c>

09:13.116 --> 09:13.126 align:start position:0%
its total momentum is conserved among
 

09:13.126 --> 09:15.716 align:start position:0%
its total momentum is conserved among
its<00:11:29.640><c> fragments.</c><00:11:30.760><c> Most</c><00:11:31.160><c> remain</c><00:11:31.520><c> trapped</c>

09:15.716 --> 09:15.726 align:start position:0%
its fragments. Most remain trapped
 

09:15.726 --> 09:17.916 align:start position:0%
its fragments. Most remain trapped
within<00:11:32.360><c> Earth's</c><00:11:32.720><c> Hill</c><00:11:33.040><c> sphere,</c><00:11:33.800><c> the</c><00:11:33.920><c> region</c>

09:17.916 --> 09:17.926 align:start position:0%
within Earth's Hill sphere, the region
 

09:17.926 --> 09:19.996 align:start position:0%
within Earth's Hill sphere, the region
of<00:11:34.320><c> space</c><00:11:34.720><c> where</c><00:11:35.000><c> Earth's</c><00:11:35.240><c> gravity</c><00:11:35.680><c> dominates</c>

09:19.996 --> 09:20.006 align:start position:0%
of space where Earth's gravity dominates
 

09:20.006 --> 09:22.196 align:start position:0%
of space where Earth's gravity dominates
over<00:11:36.480><c> the</c><00:11:36.600><c> sun's,</c><00:11:37.400><c> keeping</c><00:11:37.720><c> them</c><00:11:37.880><c> in</c><00:11:38.080><c> orbit</c>

09:22.196 --> 09:22.206 align:start position:0%
over the sun's, keeping them in orbit
 

09:22.206 --> 09:23.996 align:start position:0%
over the sun's, keeping them in orbit
around<00:11:38.880><c> our</c><00:11:39.080><c> planet.</c>

09:23.996 --> 09:24.006 align:start position:0%
around our planet.
 

09:24.006 --> 09:26.276 align:start position:0%
around our planet.
At<00:11:40.400><c> first,</c><00:11:40.680><c> these</c><00:11:40.880><c> fragments</c><00:11:41.360><c> follow</c><00:11:41.720><c> chaotic</c>

09:26.276 --> 09:26.286 align:start position:0%
At first, these fragments follow chaotic
 

09:26.286 --> 09:28.796 align:start position:0%
At first, these fragments follow chaotic
elliptical<00:11:43.120><c> paths.</c><00:11:44.000><c> Some</c><00:11:44.280><c> swing</c><00:11:44.600><c> close</c><00:11:44.880><c> to</c>

09:28.796 --> 09:28.806 align:start position:0%
elliptical paths. Some swing close to
 

09:28.806 --> 09:31.596 align:start position:0%
elliptical paths. Some swing close to
Earth,<00:11:45.640><c> others</c><00:11:46.120><c> arc</c><00:11:46.440><c> further</c><00:11:46.800><c> out.</c>

09:31.596 --> 09:31.606 align:start position:0%
Earth, others arc further out.
 

09:31.606 --> 09:33.156 align:start position:0%
Earth, others arc further out.
But<00:11:47.960><c> over</c><00:11:48.160><c> time,</c><00:11:48.800><c> they</c><00:11:48.920><c> collide</c><00:11:49.280><c> with</c><00:11:49.373><c> [music]</c>

09:33.156 --> 09:33.166 align:start position:0%
But over time, they collide with [music]
 

09:33.166 --> 09:34.276 align:start position:0%
But over time, they collide with [music]
each<00:11:49.600><c> other.</c>

09:34.276 --> 09:34.286 align:start position:0%
each other.
 

09:34.286 --> 09:37.076 align:start position:0%
each other.
Each<00:11:50.880><c> collision</c><00:11:51.480><c> transfers</c><00:11:52.080><c> momentum,</c><00:11:53.080><c> and</c>

09:37.076 --> 09:37.086 align:start position:0%
Each collision transfers momentum, and
 

09:37.086 --> 09:40.076 align:start position:0%
Each collision transfers momentum, and
gradually<00:11:54.480><c> these</c><00:11:54.880><c> wild</c><00:11:55.480><c> elliptical</c><00:11:56.000><c> orbits</c>

09:40.076 --> 09:40.086 align:start position:0%
gradually these wild elliptical orbits
 

09:40.086 --> 09:43.156 align:start position:0%
gradually these wild elliptical orbits
become<00:11:56.720><c> more</c><00:11:56.920><c> circular,</c><00:11:58.120><c> a</c><00:11:58.200><c> process</c><00:11:58.720><c> known</c><00:11:59.120><c> as</c>

09:43.156 --> 09:43.166 align:start position:0%
become more circular, a process known as
 

09:43.166 --> 09:45.676 align:start position:0%
become more circular, a process known as
collisional<00:12:00.240><c> damping.</c>

09:45.676 --> 09:45.686 align:start position:0%
collisional damping.
 

09:45.686 --> 09:47.196 align:start position:0%
collisional damping.
The<00:12:02.040><c> circulating</c><00:12:02.560><c> debris</c><00:12:03.000><c> eventually</c>

09:47.196 --> 09:47.206 align:start position:0%
The circulating debris eventually
 

09:47.206 --> 09:48.916 align:start position:0%
The circulating debris eventually
settles<00:12:03.920><c> into</c><00:12:04.160><c> a</c><00:12:04.240><c> flat</c><00:12:04.600><c> disk</c><00:12:04.840><c> around</c><00:12:05.120><c> the</c>

09:48.916 --> 09:48.926 align:start position:0%
settles into a flat disk around the
 

09:48.926 --> 09:51.636 align:start position:0%
settles into a flat disk around the
equator<00:12:06.080><c> for</c><00:12:06.200><c> a</c><00:12:06.240><c> specific</c><00:12:06.760><c> reason.</c>

09:51.636 --> 09:51.646 align:start position:0%
equator for a specific reason.
 

09:51.646 --> 09:53.956 align:start position:0%
equator for a specific reason.
You<00:12:08.040><c> see,</c><00:12:08.240><c> the</c><00:12:08.520><c> Earth</c><00:12:08.960><c> is</c><00:12:09.160><c> not</c><00:12:09.680><c> a</c><00:12:09.760><c> perfect</c>

09:53.956 --> 09:53.966 align:start position:0%
You see, the Earth is not a perfect
 

09:53.966 --> 09:56.436 align:start position:0%
You see, the Earth is not a perfect
sphere.<00:12:11.160><c> It</c><00:12:11.280><c> has</c><00:12:11.440><c> a</c><00:12:11.520><c> bulge</c><00:12:11.960><c> in</c><00:12:12.040><c> the</c><00:12:12.120><c> middle,</c>

09:56.436 --> 09:56.446 align:start position:0%
sphere. It has a bulge in the middle,
 

09:56.446 --> 09:59.156 align:start position:0%
sphere. It has a bulge in the middle,
making<00:12:13.040><c> its</c><00:12:13.280><c> equatorial</c><00:12:13.920><c> diameter</c><00:12:14.440><c> about</c><00:12:14.800><c> 43</c>

09:59.156 --> 09:59.166 align:start position:0%
making its equatorial diameter about 43
 

09:59.166 --> 10:02.396 align:start position:0%
making its equatorial diameter about 43
km<00:12:15.920><c> wider</c><00:12:16.680><c> than</c><00:12:16.880><c> its</c><00:12:17.040><c> polar</c><00:12:17.400><c> diameter.</c>

10:02.396 --> 10:02.406 align:start position:0%
km wider than its polar diameter.
 

10:02.406 --> 10:04.556 align:start position:0%
km wider than its polar diameter.
This<00:12:18.840><c> creates</c><00:12:19.240><c> an</c><00:12:19.480><c> asymmetric</c><00:12:20.200><c> gravitational</c>

10:04.556 --> 10:04.566 align:start position:0%
This creates an asymmetric gravitational
 

10:04.566 --> 10:06.596 align:start position:0%
This creates an asymmetric gravitational
field<00:12:21.280><c> and</c><00:12:21.440><c> generates</c><00:12:21.880><c> torque,</c><00:12:22.440><c> or</c>

10:06.596 --> 10:06.606 align:start position:0%
field and generates torque, or
 

10:06.606 --> 10:09.276 align:start position:0%
field and generates torque, or
rotational<00:12:23.480><c> pull,</c><00:12:23.960><c> on</c><00:12:24.120><c> nearby</c><00:12:24.480><c> debris.</c>

10:09.276 --> 10:09.286 align:start position:0%
rotational pull, on nearby debris.
 

10:09.286 --> 10:11.156 align:start position:0%
rotational pull, on nearby debris.
Gradually,<00:12:26.240><c> this</c><00:12:26.480><c> torque</c><00:12:26.840><c> draws</c><00:12:27.360><c> the</c>

10:11.156 --> 10:11.166 align:start position:0%
Gradually, this torque draws the
 

10:11.166 --> 10:13.436 align:start position:0%
Gradually, this torque draws the
material<00:12:28.000><c> orbiting</c><00:12:28.480><c> at</c><00:12:28.600><c> an</c><00:12:28.760><c> angle</c><00:12:29.440><c> into</c>

10:13.436 --> 10:13.446 align:start position:0%
material orbiting at an angle into
 

10:13.446 --> 10:15.516 align:start position:0%
material orbiting at an angle into
alignment<00:12:30.400><c> with</c><00:12:30.520><c> the</c><00:12:30.640><c> equatorial</c><00:12:31.720><c> orbital</c>

10:15.516 --> 10:15.526 align:start position:0%
alignment with the equatorial orbital
 

10:15.526 --> 10:18.316 align:start position:0%
alignment with the equatorial orbital
plane.<00:12:32.640><c> Kind</c><00:12:32.840><c> of</c><00:12:32.960><c> like</c><00:12:33.320><c> a</c><00:12:33.520><c> spinning</c><00:12:34.000><c> top</c><00:12:34.400><c> that</c>

10:18.316 --> 10:18.326 align:start position:0%
plane. Kind of like a spinning top that
 

10:18.326 --> 10:20.756 align:start position:0%
plane. Kind of like a spinning top that
wobbles,<00:12:35.440><c> but</c><00:12:35.600><c> eventually</c><00:12:36.280><c> settles</c><00:12:36.760><c> into</c><00:12:37.000><c> a</c>

10:20.756 --> 10:20.766 align:start position:0%
wobbles, but eventually settles into a
 

10:20.766 --> 10:22.236 align:start position:0%
wobbles, but eventually settles into a
stable<00:12:37.440><c> spin.</c>

10:22.236 --> 10:22.246 align:start position:0%
stable spin.
 

10:22.246 --> 10:24.356 align:start position:0%
stable spin.
And<00:12:38.680><c> this</c><00:12:38.880><c> process</c><00:12:39.440><c> wouldn't</c><00:12:39.880><c> be</c><00:12:40.040><c> unique</c><00:12:40.400><c> to</c>

10:24.356 --> 10:24.366 align:start position:0%
And this process wouldn't be unique to
 

10:24.366 --> 10:28.236 align:start position:0%
And this process wouldn't be unique to
Earth.<00:12:41.480><c> In</c><00:12:41.640><c> fact,</c><00:12:42.240><c> modeling</c><00:12:42.880><c> from</c><00:12:43.160><c> a</c><00:12:43.240><c> 2017</c>

10:28.236 --> 10:28.246 align:start position:0%
Earth. In fact, modeling from a 2017
 

10:28.246 --> 10:31.316 align:start position:0%
Earth. In fact, modeling from a 2017
study<00:12:45.240><c> suggests</c><00:12:45.720><c> that</c><00:12:46.200><c> once</c><00:12:46.480><c> upon</c><00:12:46.720><c> a</c><00:12:46.760><c> time,</c>

10:31.316 --> 10:31.326 align:start position:0%
study suggests that once upon a time,
 

10:31.326 --> 10:34.196 align:start position:0%
study suggests that once upon a time,
Mars<00:12:48.400><c> had</c><00:12:48.640><c> rings,</c><00:12:48.960><c> too.</c><00:12:49.920><c> Not</c><00:12:50.160><c> from</c><00:12:50.360><c> the</c>

10:34.196 --> 10:34.206 align:start position:0%
Mars had rings, too. Not from the
 

10:34.206 --> 10:36.996 align:start position:0%
Mars had rings, too. Not from the
breakup<00:12:51.000><c> of</c><00:12:51.160><c> a</c><00:12:51.240><c> nearby</c><00:12:51.800><c> asteroid,</c><00:12:52.839><c> but</c><00:12:53.000><c> from</c>

10:36.996 --> 10:37.006 align:start position:0%
breakup of a nearby asteroid, but from
 

10:37.006 --> 10:39.756 align:start position:0%
breakup of a nearby asteroid, but from
its<00:12:53.520><c> very</c><00:12:54.120><c> own</c><00:12:54.600><c> moon.</c>

10:39.756 --> 10:39.766 align:start position:0%
its very own moon.
 

10:39.766 --> 10:42.196 align:start position:0%
its very own moon.
Researchers<00:12:56.760><c> Andrew</c><00:12:57.160><c> Hesselbrock</c><00:12:57.960><c> and</c><00:12:58.120><c> David</c>

10:42.196 --> 10:42.206 align:start position:0%
Researchers Andrew Hesselbrock and David
 

10:42.206 --> 10:44.476 align:start position:0%
Researchers Andrew Hesselbrock and David
Minton<00:12:58.920><c> predicted</c><00:12:59.400><c> that</c><00:12:59.760><c> Phobos's</c><00:13:00.400><c> orbit</c>

10:44.476 --> 10:44.486 align:start position:0%
Minton predicted that Phobos's orbit
 

10:44.486 --> 10:45.956 align:start position:0%
Minton predicted that Phobos's orbit
will<00:13:00.920><c> bring</c><00:13:01.160><c> it</c><00:13:01.280><c> within</c><00:13:01.520><c> the</c><00:13:01.600><c> Roche</c><00:13:01.839><c> limit</c><00:13:02.160><c> in</c>

10:45.956 --> 10:45.966 align:start position:0%
will bring it within the Roche limit in
 

10:45.966 --> 10:48.396 align:start position:0%
will bring it within the Roche limit in
about<00:13:02.600><c> 70</c><00:13:03.160><c> million</c><00:13:03.560><c> years.</c>

10:48.396 --> 10:48.406 align:start position:0%
about 70 million years.
 

10:48.406 --> 10:51.036 align:start position:0%
about 70 million years.
At<00:13:04.800><c> this</c><00:13:05.000><c> point,</c><00:13:05.440><c> it</c><00:13:05.600><c> will</c><00:13:05.760><c> break</c><00:13:06.200><c> up</c><00:13:06.800><c> and</c><00:13:06.960><c> form</c>

10:51.036 --> 10:51.046 align:start position:0%
At this point, it will break up and form
 

10:51.046 --> 10:52.996 align:start position:0%
At this point, it will break up and form
a<00:13:07.480><c> ring</c><00:13:07.960><c> around</c><00:13:08.360><c> the</c><00:13:08.440><c> planet,</c><00:13:08.629><c> [music]</c>

10:52.996 --> 10:53.006 align:start position:0%
a ring around the planet, [music]
 

10:53.006 --> 10:55.316 align:start position:0%
a ring around the planet, [music]
which<00:13:09.480><c> will</c><00:13:09.640><c> eventually</c><00:13:10.120><c> deposit</c><00:13:10.600><c> about</c><00:13:10.960><c> 80%</c>

10:55.316 --> 10:55.326 align:start position:0%
which will eventually deposit about 80%
 

10:55.326 --> 10:58.116 align:start position:0%
which will eventually deposit about 80%
of<00:13:11.680><c> its</c><00:13:11.800><c> debris</c><00:13:12.280><c> onto</c><00:13:12.600><c> the</c><00:13:12.720><c> Martian</c><00:13:13.160><c> surface.</c>

10:58.116 --> 10:58.126 align:start position:0%
of its debris onto the Martian surface.
 

10:58.126 --> 11:00.836 align:start position:0%
of its debris onto the Martian surface.
The<00:13:14.440><c> remaining</c><00:13:14.880><c> 20%</c><00:13:16.000><c> will</c><00:13:16.120><c> coalesce</c><00:13:16.640><c> to</c><00:13:16.760><c> form</c>

11:00.836 --> 11:00.846 align:start position:0%
The remaining 20% will coalesce to form
 

11:00.846 --> 11:03.236 align:start position:0%
The remaining 20% will coalesce to form
a<00:13:17.240><c> new</c><00:13:17.760><c> generation</c><00:13:18.320><c> of</c><00:13:18.400><c> satellites</c><00:13:19.120><c> around</c>

11:03.236 --> 11:03.246 align:start position:0%
a new generation of satellites around
 

11:03.246 --> 11:04.676 align:start position:0%
a new generation of satellites around
the<00:13:19.600><c> red</c><00:13:19.800><c> planet.</c>

11:04.676 --> 11:04.686 align:start position:0%
the red planet.
 

11:04.686 --> 11:06.636 align:start position:0%
the red planet.
Extrapolating<00:13:21.680><c> backward,</c><00:13:22.600><c> the</c><00:13:22.720><c> pair</c>

11:06.636 --> 11:06.646 align:start position:0%
Extrapolating backward, the pair
 

11:06.646 --> 11:09.116 align:start position:0%
Extrapolating backward, the pair
suggested<00:13:23.680><c> this</c><00:13:23.920><c> cycle</c><00:13:24.360><c> has</c><00:13:24.560><c> been</c><00:13:24.720><c> going</c><00:13:25.120><c> on</c>

11:09.116 --> 11:09.126 align:start position:0%
suggested this cycle has been going on
 

11:09.126 --> 11:11.116 align:start position:0%
suggested this cycle has been going on
since<00:13:25.880><c> Mars's</c><00:13:26.320><c> birth.</c>

11:11.116 --> 11:11.126 align:start position:0%
since Mars's birth.
 

11:11.126 --> 11:13.276 align:start position:0%
since Mars's birth.
According<00:13:27.800><c> to</c><00:13:27.920><c> them,</c><00:13:28.520><c> Mars</c><00:13:28.800><c> has</c><00:13:28.960><c> gone</c><00:13:29.240><c> through</c>

11:13.276 --> 11:13.286 align:start position:0%
According to them, Mars has gone through
 

11:13.286 --> 11:17.116 align:start position:0%
According to them, Mars has gone through
three<00:13:30.360><c> to</c><00:13:30.520><c> seven</c><00:13:31.280><c> ring</c><00:13:31.760><c> satellite</c><00:13:32.360><c> cycles,</c>

11:17.116 --> 11:17.126 align:start position:0%
three to seven ring satellite cycles,
 

11:17.126 --> 11:19.076 align:start position:0%
three to seven ring satellite cycles,
and<00:13:33.520><c> they</c><00:13:33.640><c> postulate</c><00:13:34.280><c> Phobos</c><00:13:34.840><c> and</c><00:13:35.000><c> Deimos</c>

11:19.076 --> 11:19.086 align:start position:0%
and they postulate Phobos and Deimos
 

11:19.086 --> 11:21.276 align:start position:0%
and they postulate Phobos and Deimos
themselves<00:13:36.200><c> might</c><00:13:36.360><c> be</c><00:13:36.480><c> the</c><00:13:36.560><c> result</c><00:13:37.120><c> of</c><00:13:37.240><c> such</c><00:13:37.480><c> a</c>

11:21.276 --> 11:21.286 align:start position:0%
themselves might be the result of such a
 

11:21.286 --> 11:24.476 align:start position:0%
themselves might be the result of such a
process,<00:13:38.480><c> accreted</c><00:13:39.040><c> from</c><00:13:39.520><c> ring</c><00:13:39.800><c> dust</c><00:13:40.240><c> of</c><00:13:40.440><c> a</c>

11:24.476 --> 11:24.486 align:start position:0%
process, accreted from ring dust of a
 

11:24.486 --> 11:27.396 align:start position:0%
process, accreted from ring dust of a
previous<00:13:41.600><c> bigger</c><00:13:42.000><c> moon.</c>

11:27.396 --> 11:27.406 align:start position:0%
previous bigger moon.
 

11:27.406 --> 11:29.356 align:start position:0%
previous bigger moon.
Could<00:13:43.960><c> a</c><00:13:44.040><c> similar</c><00:13:44.480><c> process</c><00:13:44.880><c> be</c><00:13:45.000><c> responsible</c>

11:29.356 --> 11:29.366 align:start position:0%
Could a similar process be responsible
 

11:29.366 --> 11:31.676 align:start position:0%
Could a similar process be responsible
for<00:13:46.000><c> our</c><00:13:46.400><c> own</c><00:13:46.720><c> moon?</c>

11:31.676 --> 11:31.686 align:start position:0%
for our own moon?
 

11:31.686 --> 11:34.116 align:start position:0%
for our own moon?
Well,<00:13:48.680><c> possibly.</c>

11:34.116 --> 11:34.126 align:start position:0%
Well, possibly.
 

11:34.126 --> 11:35.956 align:start position:0%
Well, possibly.
We<00:13:50.520><c> think</c><00:13:50.840><c> our</c><00:13:51.040><c> moon</c><00:13:51.320><c> could</c><00:13:51.480><c> be</c><00:13:51.600><c> the</c><00:13:51.720><c> result</c><00:13:52.120><c> of</c>

11:35.956 --> 11:35.966 align:start position:0%
We think our moon could be the result of
 

11:35.966 --> 11:38.756 align:start position:0%
We think our moon could be the result of
a<00:13:52.360><c> violent</c><00:13:52.960><c> collision</c><00:13:53.480><c> of</c><00:13:53.800><c> two</c><00:13:54.160><c> protoplanets</c>

11:38.756 --> 11:38.766 align:start position:0%
a violent collision of two protoplanets
 

11:38.766 --> 11:42.516 align:start position:0%
a violent collision of two protoplanets
some<00:13:55.440><c> 4.5</c><00:13:56.520><c> billion</c><00:13:56.920><c> years</c><00:13:57.160><c> ago.</c><00:13:57.920><c> One</c><00:13:58.440><c> was</c><00:13:58.720><c> a</c>

11:42.516 --> 11:42.526 align:start position:0%
some 4.5 billion years ago. One was a
 

11:42.526 --> 11:45.156 align:start position:0%
some 4.5 billion years ago. One was a
newborn<00:13:59.400><c> Earth,</c><00:14:00.240><c> and</c><00:14:00.360><c> the</c><00:14:00.520><c> other</c><00:14:00.920><c> was</c><00:14:01.160><c> a</c>

11:45.156 --> 11:45.166 align:start position:0%
newborn Earth, and the other was a
 

11:45.166 --> 11:48.116 align:start position:0%
newborn Earth, and the other was a
Mars-sized<00:14:02.320><c> rock</c><00:14:02.680><c> called</c><00:14:03.200><c> Theia.</c>

11:48.116 --> 11:48.126 align:start position:0%
Mars-sized rock called Theia.
 

11:48.126 --> 11:51.036 align:start position:0%
Mars-sized rock called Theia.
This<00:14:04.600><c> impact</c><00:14:05.240><c> sent</c><00:14:05.680><c> debris</c><00:14:06.240><c> flying</c><00:14:06.960><c> into</c><00:14:07.240><c> the</c>

11:51.036 --> 11:51.046 align:start position:0%
This impact sent debris flying into the
 

11:51.046 --> 11:53.116 align:start position:0%
This impact sent debris flying into the
planet's<00:14:07.720><c> orbit,</c><00:14:08.440><c> where,</c><00:14:08.920><c> thanks</c><00:14:09.240><c> to</c>

11:53.116 --> 11:53.126 align:start position:0%
planet's orbit, where, thanks to
 

11:53.126 --> 11:55.356 align:start position:0%
planet's orbit, where, thanks to
collision<00:14:09.800><c> damping</c><00:14:10.440><c> and</c><00:14:10.800><c> the</c><00:14:10.920><c> equatorial</c>

11:55.356 --> 11:55.366 align:start position:0%
collision damping and the equatorial
 

11:55.366 --> 11:58.756 align:start position:0%
collision damping and the equatorial
bulge,<00:14:12.640><c> it</c><00:14:12.880><c> would</c><00:14:13.160><c> have</c><00:14:13.640><c> eventually</c><00:14:14.520><c> settled</c>

11:58.756 --> 11:58.766 align:start position:0%
bulge, it would have eventually settled
 

11:58.766 --> 12:00.556 align:start position:0%
bulge, it would have eventually settled
into<00:14:15.520><c> rings.</c>

12:00.556 --> 12:00.566 align:start position:0%
into rings.
 

12:00.566 --> 12:02.516 align:start position:0%
into rings.
Over<00:14:17.040><c> time,</c><00:14:17.560><c> these</c><00:14:17.920><c> fragments</c><00:14:18.480><c> would</c><00:14:18.640><c> have</c>

12:02.516 --> 12:02.526 align:start position:0%
Over time, these fragments would have
 

12:02.526 --> 12:04.716 align:start position:0%
Over time, these fragments would have
accreted<00:14:19.680><c> to</c><00:14:19.760><c> form</c><00:14:20.040><c> bigger</c><00:14:20.520><c> and</c><00:14:20.760><c> bigger</c>

12:04.716 --> 12:04.726 align:start position:0%
accreted to form bigger and bigger
 

12:04.726 --> 12:07.316 align:start position:0%
accreted to form bigger and bigger
moonlets<00:14:21.920><c> until</c><00:14:22.240><c> they</c><00:14:22.400><c> eventually</c><00:14:23.040><c> coalesced</c>

12:07.316 --> 12:07.326 align:start position:0%
moonlets until they eventually coalesced
 

12:07.326 --> 12:10.196 align:start position:0%
moonlets until they eventually coalesced
into<00:14:23.840><c> the</c><00:14:24.000><c> moon</c><00:14:24.560><c> we</c><00:14:24.680><c> see</c><00:14:24.880><c> today.</c>

12:10.196 --> 12:10.206 align:start position:0%
into the moon we see today.
 

12:10.206 --> 12:12.516 align:start position:0%
into the moon we see today.
So,<00:14:26.760><c> if</c><00:14:27.200><c> Earth</c><00:14:27.480><c> already</c><00:14:27.880><c> went</c><00:14:28.120><c> through</c><00:14:28.440><c> one</c>

12:12.516 --> 12:12.526 align:start position:0%
So, if Earth already went through one
 

12:12.526 --> 12:14.076 align:start position:0%
So, if Earth already went through one
ringed<00:14:29.240><c> phase,</c>

12:14.076 --> 12:14.086 align:start position:0%
ringed phase,
 

12:14.086 --> 12:15.476 align:start position:0%
ringed phase,
what's<00:14:30.520><c> to</c><00:14:30.640><c> say</c><00:14:30.920><c> it</c><00:14:31.000><c> didn't</c><00:14:31.200><c> go</c><00:14:31.360><c> through</c>

12:15.476 --> 12:15.486 align:start position:0%
what's to say it didn't go through
 

12:15.486 --> 12:18.916 align:start position:0%
what's to say it didn't go through
another<00:14:32.400><c> 466</c><00:14:33.520><c> million</c><00:14:33.839><c> years</c><00:14:34.040><c> ago?</c>

12:18.916 --> 12:18.926 align:start position:0%
another 466 million years ago?
 

12:18.926 --> 12:21.156 align:start position:0%
another 466 million years ago?
Rings<00:14:35.600><c> could</c><00:14:36.160><c> certainly</c><00:14:36.839><c> explain</c><00:14:37.320><c> the</c>

12:21.156 --> 12:21.166 align:start position:0%
Rings could certainly explain the
 

12:21.166 --> 12:22.876 align:start position:0%
Rings could certainly explain the
Ordovician<00:14:38.000><c> impacts.</c>

12:22.876 --> 12:22.886 align:start position:0%
Ordovician impacts.
 

12:22.886 --> 12:25.196 align:start position:0%
Ordovician impacts.
Over<00:14:39.320><c> time,</c><00:14:39.920><c> dust</c><00:14:40.280><c> and</c><00:14:40.400><c> rocky</c><00:14:40.680><c> material</c><00:14:41.160><c> from</c>

12:25.196 --> 12:25.206 align:start position:0%
Over time, dust and rocky material from
 

12:25.206 --> 12:26.956 align:start position:0%
Over time, dust and rocky material from
Earth's<00:14:41.760><c> rings</c><00:14:42.080><c> would</c><00:14:42.240><c> have</c><00:14:42.400><c> slowly</c><00:14:42.960><c> rained</c>

12:26.956 --> 12:26.966 align:start position:0%
Earth's rings would have slowly rained
 

12:26.966 --> 12:29.196 align:start position:0%
Earth's rings would have slowly rained
down<00:14:43.600><c> onto</c><00:14:43.839><c> the</c><00:14:43.920><c> surface</c><00:14:44.320><c> of</c><00:14:44.440><c> the</c><00:14:44.520><c> planet,</c>

12:29.196 --> 12:29.206 align:start position:0%
down onto the surface of the planet,
 

12:29.206 --> 12:32.076 align:start position:0%
down onto the surface of the planet,
dotting<00:14:45.960><c> impacts</c><00:14:46.640><c> all</c><00:14:46.960><c> along</c><00:14:47.320><c> the</c><00:14:47.440><c> equator,</c>

12:32.076 --> 12:32.086 align:start position:0%
dotting impacts all along the equator,
 

12:32.086 --> 12:34.956 align:start position:0%
dotting impacts all along the equator,
which<00:14:48.560><c> is</c><00:14:48.800><c> exactly</c><00:14:49.480><c> what</c><00:14:49.640><c> we</c><00:14:49.760><c> see.</c>

12:34.956 --> 12:34.966 align:start position:0%
which is exactly what we see.
 

12:34.966 --> 12:36.436 align:start position:0%
which is exactly what we see.
But,<00:14:51.360><c> the</c><00:14:51.480><c> rings</c><00:14:51.839><c> would</c><00:14:52.080><c> have</c><00:14:52.360><c> had</c>

12:36.436 --> 12:36.446 align:start position:0%
But, the rings would have had
 

12:36.446 --> 12:38.076 align:start position:0%
But, the rings would have had
consequences<00:14:53.560><c> beyond</c><00:14:53.880><c> the</c><00:14:53.920><c> impacts</c>

12:38.076 --> 12:38.086 align:start position:0%
consequences beyond the impacts
 

12:38.086 --> 12:39.396 align:start position:0%
consequences beyond the impacts
themselves.<00:14:54.740><c> [music]</c>

12:39.396 --> 12:39.406 align:start position:0%
themselves. [music]
 

12:39.406 --> 12:41.036 align:start position:0%
themselves. [music]
Tonkin<00:14:56.160><c> speculates</c><00:14:56.839><c> that</c><00:14:57.000><c> they</c><00:14:57.160><c> could</c>

12:41.036 --> 12:41.046 align:start position:0%
Tonkin speculates that they could
 

12:41.046 --> 12:44.956 align:start position:0%
Tonkin speculates that they could
explain<00:14:57.839><c> the</c><00:14:58.120><c> Hirnantian</c><00:14:59.080><c> Ice</c><00:14:59.360><c> house,</c><00:15:00.320><c> a</c><00:15:00.600><c> 8</c><00:15:01.040><c> to</c>

12:44.956 --> 12:44.966 align:start position:0%
explain the Hirnantian Ice house, a 8 to
 

12:44.966 --> 12:47.996 align:start position:0%
explain the Hirnantian Ice house, a 8 to
10°<00:15:02.280><c> global</c><00:15:02.720><c> cooling</c><00:15:03.120><c> event</c><00:15:03.480><c> that</c><00:15:03.640><c> took</c><00:15:03.839><c> place</c>

12:47.996 --> 12:48.006 align:start position:0%
10° global cooling event that took place
 

12:48.006 --> 12:49.676 align:start position:0%
10° global cooling event that took place
463

12:49.676 --> 12:49.686 align:start position:0%
463
 

12:49.686 --> 12:52.676 align:start position:0%
463
to<00:15:06.080><c> 444</c><00:15:07.360><c> million</c><00:15:07.680><c> years</c><00:15:07.920><c> ago.</c>

12:52.676 --> 12:52.686 align:start position:0%
to 444 million years ago.
 

12:52.686 --> 12:55.555 align:start position:0%
to 444 million years ago.
The<00:15:09.080><c> rings</c><00:15:09.640><c> would</c><00:15:10.000><c> have</c><00:15:10.240><c> blocked</c><00:15:10.760><c> sunlight,</c>

12:55.555 --> 12:55.565 align:start position:0%
The rings would have blocked sunlight,
 

12:55.565 --> 12:57.596 align:start position:0%
The rings would have blocked sunlight,
potentially<00:15:12.360><c> triggering</c><00:15:12.920><c> the</c><00:15:13.080><c> cooling</c>

12:57.596 --> 12:57.606 align:start position:0%
potentially triggering the cooling
 

12:57.606 --> 13:00.716 align:start position:0%
potentially triggering the cooling
despite<00:15:14.560><c> high</c><00:15:14.960><c> atmospheric</c><00:15:15.560><c> CO2.</c>

13:00.716 --> 13:00.726 align:start position:0%
despite high atmospheric CO2.
 

13:00.726 --> 13:02.996 align:start position:0%
despite high atmospheric CO2.
This<00:15:17.200><c> period</c><00:15:17.560><c> of</c><00:15:17.720><c> glaciation</c><00:15:18.600><c> is</c><00:15:18.800><c> largely</c>

13:02.996 --> 13:03.006 align:start position:0%
This period of glaciation is largely
 

13:03.006 --> 13:04.796 align:start position:0%
This period of glaciation is largely
accepted<00:15:19.720><c> as</c><00:15:19.800><c> the</c><00:15:19.960><c> leading</c><00:15:20.360><c> cause</c><00:15:20.800><c> of</c><00:15:20.920><c> the</c>

13:04.796 --> 13:04.806 align:start position:0%
accepted as the leading cause of the
 

13:04.806 --> 13:07.756 align:start position:0%
accepted as the leading cause of the
late<00:15:21.680><c> Ordovician</c><00:15:22.600><c> mass</c><00:15:22.920><c> extinction,</c><00:15:23.840><c> which</c>

13:07.756 --> 13:07.766 align:start position:0%
late Ordovician mass extinction, which
 

13:07.766 --> 13:11.556 align:start position:0%
late Ordovician mass extinction, which
killed<00:15:24.360><c> off</c><00:15:24.640><c> 85%</c><00:15:26.040><c> of</c><00:15:26.120><c> marine</c><00:15:26.480><c> life.</c>

13:11.556 --> 13:11.566 align:start position:0%
killed off 85% of marine life.
 

13:11.566 --> 13:14.556 align:start position:0%
killed off 85% of marine life.
Still,<00:15:28.600><c> even</c><00:15:29.120><c> if</c><00:15:29.560><c> Earth</c><00:15:29.840><c> did</c><00:15:30.080><c> have</c><00:15:30.360><c> rings</c><00:15:30.640><c> back</c>

13:14.556 --> 13:14.566 align:start position:0%
Still, even if Earth did have rings back
 

13:14.566 --> 13:15.516 align:start position:0%
Still, even if Earth did have rings back
then,

13:15.516 --> 13:15.526 align:start position:0%
then,
 

13:15.526 --> 13:17.476 align:start position:0%
then,
how<00:15:31.920><c> come</c><00:15:32.120><c> it</c><00:15:32.200><c> doesn't</c><00:15:32.440><c> anymore?</c><00:15:33.440><c> Where</c><00:15:33.600><c> did</c>

13:17.476 --> 13:17.486 align:start position:0%
how come it doesn't anymore? Where did
 

13:17.486 --> 13:22.156 align:start position:0%
how come it doesn't anymore? Where did
they<00:15:33.920><c> go?</c><00:15:34.720><c> And</c><00:15:35.440><c> will</c><00:15:35.800><c> they</c><00:15:36.040><c> ever</c><00:15:36.400><c> come</c><00:15:36.640><c> back?</c>

13:22.156 --> 13:22.166 align:start position:0%
they go? And will they ever come back?
 

13:22.166 --> 13:24.876 align:start position:0%
they go? And will they ever come back?
As<00:15:38.640><c> glorious</c><00:15:39.320><c> as</c><00:15:39.480><c> they</c><00:15:39.640><c> are</c><00:15:39.760><c> to</c><00:15:39.880><c> behold,</c><00:15:40.800><c> no</c>

13:24.876 --> 13:24.886 align:start position:0%
As glorious as they are to behold, no
 

13:24.886 --> 13:27.116 align:start position:0%
As glorious as they are to behold, no
planet's<00:15:41.600><c> rings</c><00:15:41.960><c> last</c><00:15:42.240><c> forever.</c>

13:27.116 --> 13:27.126 align:start position:0%
planet's rings last forever.
 

13:27.126 --> 13:29.836 align:start position:0%
planet's rings last forever.
Even<00:15:43.840><c> Saturn's</c><00:15:44.480><c> spectacular</c><00:15:45.480><c> rings</c><00:15:45.800><c> are</c><00:15:45.920><c> only</c>

13:29.836 --> 13:29.846 align:start position:0%
Even Saturn's spectacular rings are only
 

13:29.846 --> 13:31.796 align:start position:0%
Even Saturn's spectacular rings are only
predicted<00:15:46.560><c> to</c><00:15:46.640><c> last</c><00:15:46.960><c> another</c><00:15:47.240><c> 100</c><00:15:47.760><c> million</c>

13:31.796 --> 13:31.806 align:start position:0%
predicted to last another 100 million
 

13:31.806 --> 13:32.836 align:start position:0%
predicted to last another 100 million
years.

13:32.836 --> 13:32.846 align:start position:0%
years.
 

13:32.846 --> 13:34.956 align:start position:0%
years.
And<00:15:49.320><c> Earth's</c><00:15:49.640><c> rings</c><00:15:50.280><c> would</c><00:15:50.440><c> have</c><00:15:50.560><c> disappeared</c>

13:34.956 --> 13:34.966 align:start position:0%
And Earth's rings would have disappeared
 

13:34.966 --> 13:37.036 align:start position:0%
And Earth's rings would have disappeared
far<00:15:51.720><c> more</c><00:15:51.960><c> rapidly.</c>

13:37.036 --> 13:37.046 align:start position:0%
far more rapidly.
 

13:37.046 --> 13:40.676 align:start position:0%
far more rapidly.
The<00:15:53.400><c> main</c><00:15:53.640><c> culprit</c><00:15:54.560><c> is</c><00:15:54.840><c> orbital</c><00:15:55.280><c> decay.</c>

13:40.676 --> 13:40.686 align:start position:0%
The main culprit is orbital decay.
 

13:40.686 --> 13:44.236 align:start position:0%
The main culprit is orbital decay.
Any<00:15:57.200><c> material</c><00:15:57.880><c> orbiting</c><00:15:58.280><c> closer</c><00:15:58.600><c> than</c><00:15:58.800><c> 35,800</c>

13:44.236 --> 13:44.246 align:start position:0%
Any material orbiting closer than 35,800
 

13:44.246 --> 13:47.316 align:start position:0%
Any material orbiting closer than 35,800
km<00:16:01.000><c> altitude</c><00:16:01.880><c> is</c><00:16:02.080><c> considered</c><00:16:02.480><c> to</c><00:16:02.600><c> be</c><00:16:02.920><c> below</c>

13:47.316 --> 13:47.326 align:start position:0%
km altitude is considered to be below
 

13:47.326 --> 13:49.396 align:start position:0%
km altitude is considered to be below
Earth's<00:16:04.000><c> synchronous</c><00:16:04.520><c> orbit.</c>

13:49.396 --> 13:49.406 align:start position:0%
Earth's synchronous orbit.
 

13:49.406 --> 13:51.556 align:start position:0%
Earth's synchronous orbit.
We<00:16:05.800><c> aren't</c><00:16:06.000><c> sure</c><00:16:06.240><c> exactly</c><00:16:07.080><c> how</c><00:16:07.320><c> far</c><00:16:07.600><c> from</c>

13:51.556 --> 13:51.566 align:start position:0%
We aren't sure exactly how far from
 

13:51.566 --> 13:53.036 align:start position:0%
We aren't sure exactly how far from
Earth's<00:16:08.080><c> surface</c><00:16:08.600><c> its</c><00:16:08.840><c> rings</c><00:16:09.120><c> would</c><00:16:09.200><c> have</c>

13:53.036 --> 13:53.046 align:start position:0%
Earth's surface its rings would have
 

13:53.046 --> 13:55.116 align:start position:0%
Earth's surface its rings would have
been,<00:16:09.960><c> but</c><00:16:10.080><c> they</c><00:16:10.200><c> almost</c><00:16:10.640><c> certainly</c><00:16:11.240><c> would</c>

13:55.116 --> 13:55.126 align:start position:0%
been, but they almost certainly would
 

13:55.126 --> 13:57.276 align:start position:0%
been, but they almost certainly would
have<00:16:11.480><c> been</c><00:16:11.680><c> closer</c><00:16:12.080><c> than</c><00:16:12.280><c> that.</c>

13:57.276 --> 13:57.286 align:start position:0%
have been closer than that.
 

13:57.286 --> 13:58.836 align:start position:0%
have been closer than that.
In<00:16:13.640><c> this</c><00:16:13.840><c> case,</c><00:16:14.160><c> the</c><00:16:14.280><c> rings</c><00:16:14.560><c> would</c><00:16:14.800><c> orbit</c>

13:58.836 --> 13:58.846 align:start position:0%
In this case, the rings would orbit
 

13:58.846 --> 14:00.396 align:start position:0%
In this case, the rings would orbit
around<00:16:15.480><c> Earth</c><00:16:15.720><c> faster</c><00:16:16.160><c> than</c><00:16:16.320><c> the</c><00:16:16.440><c> Earth</c>

14:00.396 --> 14:00.406 align:start position:0%
around Earth faster than the Earth
 

14:00.406 --> 14:02.956 align:start position:0%
around Earth faster than the Earth
rotates<00:16:17.160><c> about</c><00:16:17.440><c> its</c><00:16:17.640><c> own</c><00:16:17.880><c> axis.</c><00:16:18.680><c> With</c><00:16:18.960><c> every</c>

14:02.956 --> 14:02.966 align:start position:0%
rotates about its own axis. With every
 

14:02.966 --> 14:05.556 align:start position:0%
rotates about its own axis. With every
swing<00:16:19.720><c> past</c><00:16:20.120><c> our</c><00:16:20.320><c> planet,</c><00:16:21.160><c> the</c><00:16:21.280><c> rings</c><00:16:21.680><c> would</c>

14:05.556 --> 14:05.566 align:start position:0%
swing past our planet, the rings would
 

14:05.566 --> 14:07.156 align:start position:0%
swing past our planet, the rings would
transfer<00:16:22.280><c> some</c><00:16:22.440><c> of</c><00:16:22.560><c> that</c><00:16:22.760><c> orbital</c><00:16:23.080><c> motion</c>

14:07.156 --> 14:07.166 align:start position:0%
transfer some of that orbital motion
 

14:07.166 --> 14:09.876 align:start position:0%
transfer some of that orbital motion
energy<00:16:23.960><c> to</c><00:16:24.080><c> make</c><00:16:24.360><c> the</c><00:16:24.600><c> Earth</c><00:16:24.880><c> spin</c><00:16:25.240><c> a</c><00:16:25.360><c> tiny</c><00:16:25.920><c> bit</c>

14:09.876 --> 14:09.886 align:start position:0%
energy to make the Earth spin a tiny bit
 

14:09.886 --> 14:11.236 align:start position:0%
energy to make the Earth spin a tiny bit
faster.

14:11.236 --> 14:11.246 align:start position:0%
faster.
 

14:11.246 --> 14:13.156 align:start position:0%
faster.
The<00:16:27.640><c> Earth's</c><00:16:28.000><c> slower</c><00:16:28.440><c> rotation</c><00:16:29.080><c> would</c><00:16:29.280><c> act</c>

14:13.156 --> 14:13.166 align:start position:0%
The Earth's slower rotation would act
 

14:13.166 --> 14:15.636 align:start position:0%
The Earth's slower rotation would act
like<00:16:29.600><c> a</c><00:16:29.640><c> brake,</c><00:16:30.520><c> sapping</c><00:16:31.160><c> energy</c><00:16:31.640><c> from</c><00:16:31.839><c> the</c>

14:15.636 --> 14:15.646 align:start position:0%
like a brake, sapping energy from the
 

14:15.646 --> 14:18.436 align:start position:0%
like a brake, sapping energy from the
rings,<00:16:32.760><c> causing</c><00:16:33.200><c> their</c><00:16:33.480><c> orbital</c><00:16:33.920><c> radius,</c>

14:18.436 --> 14:18.446 align:start position:0%
rings, causing their orbital radius,
 

14:18.446 --> 14:20.796 align:start position:0%
rings, causing their orbital radius,
period,<00:16:35.320><c> and</c><00:16:35.520><c> altitude</c><00:16:36.240><c> to</c><00:16:36.320><c> decrease</c><00:16:36.921><c> [music]</c>

14:20.796 --> 14:20.806 align:start position:0%
period, and altitude to decrease [music]
 

14:20.806 --> 14:23.116 align:start position:0%
period, and altitude to decrease [music]
until<00:16:37.360><c> they</c><00:16:37.480><c> fell</c><00:16:37.839><c> into</c><00:16:38.080><c> the</c><00:16:38.200><c> planet.</c>

14:23.116 --> 14:23.126 align:start position:0%
until they fell into the planet.
 

14:23.126 --> 14:25.156 align:start position:0%
until they fell into the planet.
Atmospheric<00:16:39.920><c> drag</c><00:16:40.280><c> from</c><00:16:40.480><c> Earth's</c><00:16:40.720><c> exosphere</c>

14:25.156 --> 14:25.166 align:start position:0%
Atmospheric drag from Earth's exosphere
 

14:25.166 --> 14:27.876 align:start position:0%
Atmospheric drag from Earth's exosphere
would<00:16:41.720><c> only</c><00:16:42.080><c> accelerate</c><00:16:42.760><c> this</c><00:16:42.920><c> process.</c>

14:27.876 --> 14:27.886 align:start position:0%
would only accelerate this process.
 

14:27.886 --> 14:31.636 align:start position:0%
would only accelerate this process.
Extending<00:16:44.720><c> from</c><00:16:45.160><c> 700</c><00:16:45.880><c> to</c><00:16:46.120><c> 10,000</c><00:16:47.240><c> km</c><00:16:47.680><c> above</c>

14:31.636 --> 14:31.646 align:start position:0%
Extending from 700 to 10,000 km above
 

14:31.646 --> 14:34.036 align:start position:0%
Extending from 700 to 10,000 km above
the<00:16:48.040><c> surface,</c><00:16:48.880><c> this</c><00:16:49.080><c> part</c><00:16:49.440><c> of</c><00:16:49.520><c> our</c><00:16:49.720><c> atmosphere</c>

14:34.036 --> 14:34.046 align:start position:0%
the surface, this part of our atmosphere
 

14:34.046 --> 14:36.116 align:start position:0%
the surface, this part of our atmosphere
is<00:16:50.480><c> incredibly</c><00:16:51.160><c> tenuous.</c>

14:36.116 --> 14:36.126 align:start position:0%
is incredibly tenuous.
 

14:36.126 --> 14:37.596 align:start position:0%
is incredibly tenuous.
Although<00:16:52.800><c> it's</c><00:16:53.000><c> still</c><00:16:53.240><c> dense</c><00:16:53.520><c> enough</c><00:16:53.760><c> to</c>

14:37.596 --> 14:37.606 align:start position:0%
Although it's still dense enough to
 

14:37.606 --> 14:40.396 align:start position:0%
Although it's still dense enough to
create<00:16:54.200><c> friction</c><00:16:54.760><c> on</c><00:16:55.040><c> orbiting</c><00:16:55.440><c> particles.</c>

14:40.396 --> 14:40.406 align:start position:0%
create friction on orbiting particles.
 

14:40.406 --> 14:42.396 align:start position:0%
create friction on orbiting particles.
Each<00:16:56.960><c> pass</c><00:16:57.320><c> through</c><00:16:57.520><c> the</c><00:16:57.640><c> exosphere</c><00:16:58.400><c> would</c>

14:42.396 --> 14:42.406 align:start position:0%
Each pass through the exosphere would
 

14:42.406 --> 14:45.596 align:start position:0%
Each pass through the exosphere would
slow<00:16:59.200><c> the</c><00:16:59.360><c> material</c><00:16:59.960><c> down</c><00:17:00.280><c> slightly.</c><00:17:01.680><c> Over</c>

14:45.596 --> 14:45.606 align:start position:0%
slow the material down slightly. Over
 

14:45.606 --> 14:47.596 align:start position:0%
slow the material down slightly. Over
thousands<00:17:02.320><c> of</c><00:17:02.480><c> orbits,</c><00:17:03.080><c> this</c><00:17:03.320><c> would</c><00:17:03.560><c> pull</c>

14:47.596 --> 14:47.606 align:start position:0%
thousands of orbits, this would pull
 

14:47.606 --> 14:49.276 align:start position:0%
thousands of orbits, this would pull
fragments<00:17:04.360><c> into</c><00:17:04.640><c> lower</c><00:17:05.120><c> and</c><00:17:05.319><c> lower</c>

14:49.276 --> 14:49.286 align:start position:0%
fragments into lower and lower
 

14:49.286 --> 14:51.516 align:start position:0%
fragments into lower and lower
trajectories<00:17:06.640><c> until</c><00:17:06.920><c> they</c><00:17:07.079><c> burn</c><00:17:07.439><c> up</c><00:17:07.600><c> in</c><00:17:07.680><c> the</c>

14:51.516 --> 14:51.526 align:start position:0%
trajectories until they burn up in the
 

14:51.526 --> 14:55.476 align:start position:0%
trajectories until they burn up in the
atmosphere<00:17:08.640><c> or</c><00:17:09.040><c> impact</c><00:17:09.480><c> the</c><00:17:09.560><c> planet</c><00:17:09.920><c> below.</c>

14:55.476 --> 14:55.486 align:start position:0%
atmosphere or impact the planet below.
 

14:55.486 --> 14:57.155 align:start position:0%
atmosphere or impact the planet below.
From<00:17:11.920><c> the</c><00:17:12.040><c> surface</c><00:17:12.520><c> of</c><00:17:12.600><c> the</c><00:17:12.800><c> Ordovician</c>

14:57.155 --> 14:57.165 align:start position:0%
From the surface of the Ordovician
 

14:57.165 --> 14:59.876 align:start position:0%
From the surface of the Ordovician
Earth,<00:17:14.160><c> it</c><00:17:14.280><c> would</c><00:17:14.439><c> seem</c><00:17:14.760><c> as</c><00:17:14.880><c> though</c><00:17:15.120><c> the</c><00:17:15.280><c> sky</c>

14:59.876 --> 14:59.886 align:start position:0%
Earth, it would seem as though the sky
 

14:59.886 --> 15:01.756 align:start position:0%
Earth, it would seem as though the sky
were<00:17:16.319><c> literally</c><00:17:16.880><c> falling.</c>

15:01.756 --> 15:01.766 align:start position:0%
were literally falling.
 

15:01.766 --> 15:04.116 align:start position:0%
were literally falling.
Not<00:17:18.319><c> always</c><00:17:18.720><c> dramatically,</c><00:17:19.640><c> the</c><00:17:19.760><c> majority</c><00:17:20.319><c> of</c>

15:04.116 --> 15:04.126 align:start position:0%
Not always dramatically, the majority of
 

15:04.126 --> 15:05.915 align:start position:0%
Not always dramatically, the majority of
the<00:17:20.520><c> ring</c><00:17:20.720><c> material</c><00:17:21.160><c> would</c><00:17:21.400><c> tumble</c><00:17:21.720><c> down</c><00:17:22.040><c> as</c>

15:05.915 --> 15:05.925 align:start position:0%
the ring material would tumble down as
 

15:05.925 --> 15:06.956 align:start position:0%
the ring material would tumble down as
dust.

15:06.956 --> 15:06.966 align:start position:0%
dust.
 

15:06.966 --> 15:09.356 align:start position:0%
dust.
But<00:17:23.319><c> occasionally,</c><00:17:24.079><c> when</c><00:17:24.319><c> a</c><00:17:24.600><c> larger</c><00:17:25.160><c> fragment</c>

15:09.356 --> 15:09.366 align:start position:0%
But occasionally, when a larger fragment
 

15:09.366 --> 15:11.915 align:start position:0%
But occasionally, when a larger fragment
deorbits,<00:17:26.640><c> a</c><00:17:26.760><c> brilliant</c><00:17:27.439><c> fireball</c><00:17:28.000><c> would</c>

15:11.915 --> 15:11.925 align:start position:0%
deorbits, a brilliant fireball would
 

15:11.925 --> 15:14.076 align:start position:0%
deorbits, a brilliant fireball would
streak<00:17:28.720><c> across</c><00:17:29.080><c> the</c><00:17:29.200><c> sky.</c>

15:14.076 --> 15:14.086 align:start position:0%
streak across the sky.
 

15:14.086 --> 15:15.916 align:start position:0%
streak across the sky.
As<00:17:30.520><c> it</c><00:17:30.680><c> fell</c><00:17:30.920><c> into</c><00:17:31.200><c> Earth,</c><00:17:31.720><c> it</c><00:17:31.840><c> would</c><00:17:31.960><c> grow</c>

15:15.916 --> 15:15.926 align:start position:0%
As it fell into Earth, it would grow
 

15:15.926 --> 15:18.956 align:start position:0%
As it fell into Earth, it would grow
bigger<00:17:32.920><c> and</c><00:17:33.080><c> bigger</c><00:17:33.880><c> until</c><00:17:34.200><c> it</c><00:17:34.360><c> slammed</c><00:17:35.000><c> into</c>

15:18.956 --> 15:18.966 align:start position:0%
bigger and bigger until it slammed into
 

15:18.966 --> 15:22.476 align:start position:0%
bigger and bigger until it slammed into
the<00:17:35.360><c> ground</c><00:17:35.960><c> somewhere</c><00:17:36.560><c> along</c><00:17:36.920><c> the</c><00:17:37.080><c> equator.</c>

15:22.476 --> 15:22.486 align:start position:0%
the ground somewhere along the equator.
 

15:22.486 --> 15:23.956 align:start position:0%
the ground somewhere along the equator.
Along<00:17:38.960><c> with</c><00:17:39.080><c> gravity,</c>

15:23.956 --> 15:23.966 align:start position:0%
Along with gravity,
 

15:23.966 --> 15:26.036 align:start position:0%
Along with gravity,
our<00:17:40.440><c> rings</c><00:17:40.720><c> would</c><00:17:40.880><c> also</c><00:17:41.200><c> have</c><00:17:41.480><c> the</c><00:17:41.600><c> sun</c><00:17:42.160><c> to</c>

15:26.036 --> 15:26.046 align:start position:0%
our rings would also have the sun to
 

15:26.046 --> 15:27.476 align:start position:0%
our rings would also have the sun to
contend<00:17:42.760><c> with.</c>

15:27.476 --> 15:27.486 align:start position:0%
contend with.
 

15:27.486 --> 15:29.036 align:start position:0%
contend with.
Charged<00:17:44.080><c> particles</c><00:17:44.560><c> from</c><00:17:44.720><c> our</c><00:17:44.880><c> sun</c><00:17:45.160><c> would</c>

15:29.036 --> 15:29.046 align:start position:0%
Charged particles from our sun would
 

15:29.046 --> 15:31.476 align:start position:0%
Charged particles from our sun would
constantly<00:17:46.000><c> bombard</c><00:17:46.520><c> the</c><00:17:46.640><c> ring</c><00:17:46.800><c> material,</c>

15:31.476 --> 15:31.486 align:start position:0%
constantly bombard the ring material,
 

15:31.486 --> 15:33.676 align:start position:0%
constantly bombard the ring material,
stripping<00:17:48.360><c> off</c><00:17:48.600><c> electrons.</c>

15:33.676 --> 15:33.686 align:start position:0%
stripping off electrons.
 

15:33.686 --> 15:35.436 align:start position:0%
stripping off electrons.
The<00:17:50.000><c> resulting</c><00:17:50.600><c> positive</c><00:17:51.040><c> particles</c><00:17:51.600><c> would</c>

15:35.436 --> 15:35.446 align:start position:0%
The resulting positive particles would
 

15:35.446 --> 15:37.076 align:start position:0%
The resulting positive particles would
then<00:17:51.880><c> become</c><00:17:52.160><c> trapped</c><00:17:52.560><c> in</c><00:17:52.680><c> Earth's</c><00:17:52.920><c> magnetic</c>

15:37.076 --> 15:37.086 align:start position:0%
then become trapped in Earth's magnetic
 

15:37.086 --> 15:39.436 align:start position:0%
then become trapped in Earth's magnetic
field<00:17:53.640><c> lines</c><00:17:54.320><c> and</c><00:17:54.440><c> get</c><00:17:54.680><c> funneled</c><00:17:55.040><c> down</c><00:17:55.400><c> toward</c>

15:39.436 --> 15:39.446 align:start position:0%
field lines and get funneled down toward
 

15:39.446 --> 15:41.516 align:start position:0%
field lines and get funneled down toward
the<00:17:55.800><c> poles</c><00:17:56.360><c> and</c><00:17:56.440><c> the</c><00:17:56.560><c> equator.</c>

15:41.516 --> 15:41.526 align:start position:0%
the poles and the equator.
 

15:41.526 --> 15:43.196 align:start position:0%
the poles and the equator.
Eventually,<00:17:58.280><c> they'd</c><00:17:58.560><c> slam</c><00:17:59.000><c> into</c><00:17:59.200><c> the</c><00:17:59.280><c> upper</c>

15:43.196 --> 15:43.206 align:start position:0%
Eventually, they'd slam into the upper
 

15:43.206 --> 15:45.916 align:start position:0%
Eventually, they'd slam into the upper
atmosphere,<00:18:00.360><c> giving</c><00:18:00.640><c> off</c><00:18:00.840><c> a</c><00:18:00.960><c> dull</c><00:18:01.440><c> glow</c>

15:45.916 --> 15:45.926 align:start position:0%
atmosphere, giving off a dull glow
 

15:45.926 --> 15:48.516 align:start position:0%
atmosphere, giving off a dull glow
before<00:18:02.560><c> disappearing</c><00:18:03.280><c> forever.</c>

15:48.516 --> 15:48.526 align:start position:0%
before disappearing forever.
 

15:48.526 --> 15:51.116 align:start position:0%
before disappearing forever.
Looking<00:18:05.160><c> up</c><00:18:05.480><c> from</c><00:18:05.760><c> an</c><00:18:05.960><c> ancient</c><00:18:06.360><c> Earth,</c><00:18:07.200><c> you'd</c>

15:51.116 --> 15:51.126 align:start position:0%
Looking up from an ancient Earth, you'd
 

15:51.126 --> 15:53.396 align:start position:0%
Looking up from an ancient Earth, you'd
see<00:18:07.760><c> a</c><00:18:07.920><c> dim</c><00:18:08.560><c> curtain</c><00:18:09.000><c> of</c><00:18:09.160><c> light</c><00:18:09.480><c> in</c><00:18:09.600><c> the</c>

15:53.396 --> 15:53.406 align:start position:0%
see a dim curtain of light in the
 

15:53.406 --> 15:56.476 align:start position:0%
see a dim curtain of light in the
high-altitude<00:18:10.520><c> sky,</c><00:18:11.400><c> kind</c><00:18:11.600><c> of</c><00:18:11.720><c> like</c><00:18:12.000><c> a</c><00:18:12.120><c> faint</c>

15:56.476 --> 15:56.486 align:start position:0%
high-altitude sky, kind of like a faint
 

15:56.486 --> 15:58.596 align:start position:0%
high-altitude sky, kind of like a faint
localized<00:18:13.400><c> aurora.</c>

15:58.596 --> 15:58.606 align:start position:0%
localized aurora.
 

15:58.606 --> 16:01.556 align:start position:0%
localized aurora.
But<00:18:15.360><c> this</c><00:18:15.560><c> light</c><00:18:15.800><c> show</c><00:18:16.040><c> can't</c><00:18:16.320><c> go</c><00:18:16.440><c> on</c><00:18:16.600><c> forever.</c>

16:01.556 --> 16:01.566 align:start position:0%
But this light show can't go on forever.
 

16:01.566 --> 16:04.436 align:start position:0%
But this light show can't go on forever.
Every<00:18:18.160><c> glowing</c><00:18:18.560><c> speck</c><00:18:19.360><c> represents</c><00:18:19.960><c> material</c>

16:04.436 --> 16:04.446 align:start position:0%
Every glowing speck represents material
 

16:04.446 --> 16:06.436 align:start position:0%
Every glowing speck represents material
lost<00:18:21.040><c> from</c><00:18:21.200><c> the</c><00:18:21.320><c> rings.</c>

16:06.436 --> 16:06.446 align:start position:0%
lost from the rings.
 

16:06.446 --> 16:08.276 align:start position:0%
lost from the rings.
We<00:18:22.800><c> also</c><00:18:23.080><c> can't</c><00:18:23.360><c> forget</c><00:18:23.680><c> the</c><00:18:23.760><c> effects</c><00:18:24.240><c> of</c><00:18:24.400><c> the</c>

16:08.276 --> 16:08.286 align:start position:0%
We also can't forget the effects of the
 

16:08.286 --> 16:10.276 align:start position:0%
We also can't forget the effects of the
moon's<00:18:25.000><c> gravity.</c>

16:10.276 --> 16:10.286 align:start position:0%
moon's gravity.
 

16:10.286 --> 16:12.556 align:start position:0%
moon's gravity.
Every<00:18:26.760><c> time</c><00:18:27.200><c> it</c><00:18:27.520><c> passes</c><00:18:27.960><c> overhead,</c><00:18:28.720><c> the</c>

16:12.556 --> 16:12.566 align:start position:0%
Every time it passes overhead, the
 

16:12.566 --> 16:14.276 align:start position:0%
Every time it passes overhead, the
moon's<00:18:29.280><c> gravity</c><00:18:29.800><c> would</c><00:18:30.000><c> tug</c><00:18:30.237><c> [music]</c><00:18:30.400><c> on</c>

16:14.276 --> 16:14.286 align:start position:0%
moon's gravity would tug [music] on
 

16:14.286 --> 16:16.316 align:start position:0%
moon's gravity would tug [music] on
nearby<00:18:31.000><c> ring</c><00:18:31.200><c> particles.</c>

16:16.316 --> 16:16.326 align:start position:0%
nearby ring particles.
 

16:16.326 --> 16:17.836 align:start position:0%
nearby ring particles.
For<00:18:32.640><c> particles</c><00:18:33.200><c> at</c><00:18:33.400><c> certain</c><00:18:33.800><c> orbital</c>

16:17.836 --> 16:17.846 align:start position:0%
For particles at certain orbital
 

16:17.846 --> 16:20.596 align:start position:0%
For particles at certain orbital
distances,<00:18:35.240><c> this</c><00:18:35.480><c> would</c><00:18:35.680><c> happen</c><00:18:36.080><c> repeatedly</c>

16:20.596 --> 16:20.606 align:start position:0%
distances, this would happen repeatedly
 

16:20.606 --> 16:22.716 align:start position:0%
distances, this would happen repeatedly
at<00:18:37.000><c> the</c><00:18:37.080><c> same</c><00:18:37.440><c> point</c><00:18:37.760><c> in</c><00:18:37.840><c> their</c><00:18:38.080><c> orbit,</c><00:18:38.920><c> a</c>

16:22.716 --> 16:22.726 align:start position:0%
at the same point in their orbit, a
 

16:22.726 --> 16:25.876 align:start position:0%
at the same point in their orbit, a
phenomenon<00:18:39.720><c> called</c><00:18:40.360><c> orbital</c><00:18:41.000><c> resonance.</c>

16:25.876 --> 16:25.886 align:start position:0%
phenomenon called orbital resonance.
 

16:25.886 --> 16:28.156 align:start position:0%
phenomenon called orbital resonance.
The<00:18:42.240><c> repeated</c><00:18:42.840><c> gravitational</c><00:18:43.520><c> kicks</c><00:18:44.320><c> would</c>

16:28.156 --> 16:28.166 align:start position:0%
The repeated gravitational kicks would
 

16:28.166 --> 16:30.596 align:start position:0%
The repeated gravitational kicks would
destabilize<00:18:45.240><c> the</c><00:18:45.320><c> rings'</c><00:18:45.600><c> paths,</c><00:18:46.360><c> ejecting</c>

16:30.596 --> 16:30.606 align:start position:0%
destabilize the rings' paths, ejecting
 

16:30.606 --> 16:33.076 align:start position:0%
destabilize the rings' paths, ejecting
some<00:18:47.040><c> particles</c><00:18:47.680><c> outward</c><00:18:48.040><c> into</c><00:18:48.280><c> space</c><00:18:49.200><c> and</c>

16:33.076 --> 16:33.086 align:start position:0%
some particles outward into space and
 

16:33.086 --> 16:35.276 align:start position:0%
some particles outward into space and
nudging<00:18:49.720><c> others</c><00:18:50.080><c> inward,</c><00:18:50.800><c> in</c><00:18:50.920><c> this</c><00:18:51.080><c> case</c>

16:35.276 --> 16:35.286 align:start position:0%
nudging others inward, in this case
 

16:35.286 --> 16:36.796 align:start position:0%
nudging others inward, in this case
toward<00:18:52.000><c> Earth.</c>

16:36.796 --> 16:36.806 align:start position:0%
toward Earth.
 

16:36.806 --> 16:38.876 align:start position:0%
toward Earth.
Over<00:18:53.240><c> millions</c><00:18:53.680><c> of</c><00:18:53.800><c> years,</c><00:18:54.080><c> these</c><00:18:54.320><c> resonances</c>

16:38.876 --> 16:38.886 align:start position:0%
Over millions of years, these resonances
 

16:38.886 --> 16:41.196 align:start position:0%
Over millions of years, these resonances
would<00:18:55.400><c> carve</c><00:18:55.920><c> gaps</c><00:18:56.440><c> through</c><00:18:56.680><c> the</c><00:18:56.760><c> rings,</c>

16:41.196 --> 16:41.206 align:start position:0%
would carve gaps through the rings,
 

16:41.206 --> 16:43.476 align:start position:0%
would carve gaps through the rings,
accelerating<00:18:58.360><c> their</c><00:18:58.560><c> collapse.</c>

16:43.476 --> 16:43.486 align:start position:0%
accelerating their collapse.
 

16:43.486 --> 16:45.716 align:start position:0%
accelerating their collapse.
We<00:18:59.880><c> think</c><00:19:00.280><c> Earth's</c><00:19:00.600><c> rings</c><00:19:00.920><c> disappeared</c><00:19:01.600><c> after</c>

16:45.716 --> 16:45.726 align:start position:0%
We think Earth's rings disappeared after
 

16:45.726 --> 16:48.516 align:start position:0%
We think Earth's rings disappeared after
about<00:19:02.440><c> 40</c><00:19:02.840><c> million</c><00:19:03.200><c> years</c><00:19:03.880><c> because</c><00:19:04.240><c> this</c><00:19:04.600><c> is</c>

16:48.516 --> 16:48.526 align:start position:0%
about 40 million years because this is
 

16:48.526 --> 16:50.556 align:start position:0%
about 40 million years because this is
when<00:19:05.040><c> the</c><00:19:05.280><c> L</c><00:19:05.680><c> chondrite</c><00:19:06.280><c> spike</c><00:19:06.680><c> in</c><00:19:06.760><c> the</c>

16:50.556 --> 16:50.566 align:start position:0%
when the L chondrite spike in the
 

16:50.566 --> 16:53.636 align:start position:0%
when the L chondrite spike in the
geological<00:19:07.440><c> record</c><00:19:07.840><c> ends,</c><00:19:08.640><c> no</c><00:19:08.960><c> more</c><00:19:09.480><c> asteroid</c>

16:53.636 --> 16:53.646 align:start position:0%
geological record ends, no more asteroid
 

16:53.646 --> 16:55.276 align:start position:0%
geological record ends, no more asteroid
bombardment.

16:55.276 --> 16:55.286 align:start position:0%
bombardment.
 

16:55.286 --> 16:57.156 align:start position:0%
bombardment.
But<00:19:11.680><c> Tompkins</c><00:19:12.200><c> is</c><00:19:12.360><c> confident</c><00:19:12.840><c> we</c><00:19:13.040><c> haven't</c>

16:57.156 --> 16:57.166 align:start position:0%
But Tompkins is confident we haven't
 

16:57.166 --> 16:59.196 align:start position:0%
But Tompkins is confident we haven't
seen<00:19:13.680><c> the</c><00:19:13.840><c> last</c><00:19:14.320><c> of</c><00:19:14.440><c> our</c><00:19:14.600><c> rocky</c><00:19:14.880><c> companions,</c>

16:59.196 --> 16:59.206 align:start position:0%
seen the last of our rocky companions,
 

16:59.206 --> 17:01.436 align:start position:0%
seen the last of our rocky companions,
saying,<00:19:16.400><c> "This</c><00:19:16.600><c> wasn't</c><00:19:16.960><c> the</c><00:19:17.040><c> first</c><00:19:17.400><c> time</c>

17:01.436 --> 17:01.446 align:start position:0%
saying, "This wasn't the first time
 

17:01.446 --> 17:03.396 align:start position:0%
saying, "This wasn't the first time
Earth<00:19:17.960><c> had</c><00:19:18.120><c> a</c><00:19:18.200><c> ring,</c><00:19:19.000><c> and</c><00:19:19.120><c> it</c><00:19:19.240><c> won't</c><00:19:19.400><c> be</c><00:19:19.520><c> the</c>

17:03.396 --> 17:03.406 align:start position:0%
Earth had a ring, and it won't be the
 

17:03.406 --> 17:05.436 align:start position:0%
Earth had a ring, and it won't be the
last,<00:19:20.280><c> most</c><00:19:20.480><c> likely."</c>

17:05.436 --> 17:05.446 align:start position:0%
last, most likely."
 

17:05.446 --> 17:07.756 align:start position:0%
last, most likely."
But,<00:19:21.880><c> if</c><00:19:22.120><c> Earth</c><00:19:22.440><c> had</c><00:19:22.760><c> rings</c><00:19:23.040><c> today,</c><00:19:23.560><c> how</c><00:19:23.840><c> would</c>

17:07.756 --> 17:07.766 align:start position:0%
But, if Earth had rings today, how would
 

17:07.766 --> 17:09.036 align:start position:0%
But, if Earth had rings today, how would
it<00:19:24.160><c> affect</c><00:19:24.560><c> us?</c>

17:09.036 --> 17:09.046 align:start position:0%
it affect us?
 

17:09.046 --> 17:11.636 align:start position:0%
it affect us?
Would<00:19:25.520><c> its</c><00:19:25.640><c> satellites</c><00:19:26.200><c> survive?</c><00:19:27.360><c> How</c><00:19:27.720><c> would</c>

17:11.636 --> 17:11.646 align:start position:0%
Would its satellites survive? How would
 

17:11.646 --> 17:14.716 align:start position:0%
Would its satellites survive? How would
we<00:19:28.080><c> get</c><00:19:28.320><c> into</c><00:19:28.560><c> space?</c><00:19:29.720><c> Or,</c><00:19:30.120><c> would</c><00:19:30.320><c> we</c><00:19:30.440><c> just</c><00:19:30.760><c> end</c>

17:14.716 --> 17:14.726 align:start position:0%
we get into space? Or, would we just end
 

17:14.726 --> 17:17.716 align:start position:0%
we get into space? Or, would we just end
up<00:19:31.400><c> pulverized</c><00:19:32.080><c> by</c><00:19:32.440><c> a</c><00:19:32.600><c> brutal</c><00:19:33.120><c> impact</c><00:19:33.600><c> from</c>

17:17.716 --> 17:17.726 align:start position:0%
up pulverized by a brutal impact from
 

17:17.726 --> 17:20.916 align:start position:0%
up pulverized by a brutal impact from
infalling<00:19:34.520><c> debris?</c>

17:20.916 --> 17:20.926 align:start position:0%
 
 

17:20.926 --> 17:23.156 align:start position:0%
 
Let's<00:19:37.440><c> assume</c><00:19:38.080><c> Earth's</c><00:19:38.440><c> hypothetical</c><00:19:39.120><c> ring</c>

17:23.156 --> 17:23.166 align:start position:0%
Let's assume Earth's hypothetical ring
 

17:23.166 --> 17:25.156 align:start position:0%
Let's assume Earth's hypothetical ring
sit<00:19:39.680><c> somewhere</c><00:19:40.040><c> between</c><00:19:40.440><c> the</c><00:19:40.560><c> thermosphere</c>

17:25.156 --> 17:25.166 align:start position:0%
sit somewhere between the thermosphere
 

17:25.166 --> 17:28.516 align:start position:0%
sit somewhere between the thermosphere
and<00:19:41.800><c> geostationary</c><00:19:42.680><c> orbit,</c><00:19:43.560><c> between</c><00:19:43.920><c> 700</c><00:19:44.600><c> to</c>

17:28.516 --> 17:28.526 align:start position:0%
and geostationary orbit, between 700 to
 

17:28.526 --> 17:30.396 align:start position:0%
and geostationary orbit, between 700 to
35,800

17:30.396 --> 17:30.406 align:start position:0%
35,800
 

17:30.406 --> 17:31.916 align:start position:0%
35,800
km<00:19:47.160><c> up.</c>

17:31.916 --> 17:31.926 align:start position:0%
km up.
 

17:31.926 --> 17:33.476 align:start position:0%
km up.
Commercial<00:19:48.680><c> airplanes</c><00:19:49.120><c> don't</c><00:19:49.320><c> fly</c><00:19:49.520><c> high</c>

17:33.476 --> 17:33.486 align:start position:0%
Commercial airplanes don't fly high
 

17:33.486 --> 17:35.316 align:start position:0%
Commercial airplanes don't fly high
enough,<00:19:50.120><c> so</c><00:19:50.680><c> they</c><00:19:50.920><c> wouldn't</c><00:19:51.160><c> have</c><00:19:51.320><c> to</c><00:19:51.400><c> worry</c>

17:35.316 --> 17:35.326 align:start position:0%
enough, so they wouldn't have to worry
 

17:35.326 --> 17:37.476 align:start position:0%
enough, so they wouldn't have to worry
about<00:19:51.840><c> navigating</c><00:19:52.400><c> the</c><00:19:52.480><c> ring</c><00:19:52.680><c> itself.</c>

17:37.476 --> 17:37.486 align:start position:0%
about navigating the ring itself.
 

17:37.486 --> 17:38.876 align:start position:0%
about navigating the ring itself.
But,<00:19:53.840><c> they</c><00:19:53.960><c> still</c><00:19:54.240><c> face</c><00:19:54.480><c> danger</c><00:19:54.840><c> from</c>

17:38.876 --> 17:38.886 align:start position:0%
But, they still face danger from
 

17:38.886 --> 17:41.396 align:start position:0%
But, they still face danger from
infalling<00:19:55.880><c> ring</c><00:19:56.160><c> debris,</c><00:19:57.040><c> burning</c><00:19:57.360><c> up</c><00:19:57.480><c> as</c>

17:41.396 --> 17:41.406 align:start position:0%
infalling ring debris, burning up as
 

17:41.406 --> 17:43.756 align:start position:0%
infalling ring debris, burning up as
meteors<00:19:58.360><c> on</c><00:19:58.480><c> their</c><00:19:58.600><c> way</c><00:19:58.800><c> down.</c>

17:43.756 --> 17:43.766 align:start position:0%
meteors on their way down.
 

17:43.766 --> 17:45.596 align:start position:0%
meteors on their way down.
Flight<00:20:00.280><c> paths</c><00:20:00.600><c> near</c><00:20:00.800><c> the</c><00:20:00.920><c> equator</c><00:20:01.440><c> would</c><00:20:01.600><c> need</c>

17:45.596 --> 17:45.606 align:start position:0%
Flight paths near the equator would need
 

17:45.606 --> 17:47.636 align:start position:0%
Flight paths near the equator would need
constant<00:20:02.480><c> monitoring</c><00:20:03.120><c> for</c><00:20:03.440><c> incoming</c>

17:47.636 --> 17:47.646 align:start position:0%
constant monitoring for incoming
 

17:47.646 --> 17:49.156 align:start position:0%
constant monitoring for incoming
fragments.

17:49.156 --> 17:49.166 align:start position:0%
fragments.
 

17:49.166 --> 17:50.996 align:start position:0%
fragments.
A<00:20:05.480><c> much</c><00:20:05.720><c> bigger</c><00:20:05.960><c> challenge</c><00:20:06.400><c> is</c><00:20:06.720><c> what</c><00:20:06.920><c> to</c><00:20:07.040><c> do</c>

17:50.996 --> 17:51.006 align:start position:0%
A much bigger challenge is what to do
 

17:51.006 --> 17:53.076 align:start position:0%
A much bigger challenge is what to do
with<00:20:07.560><c> satellites.</c>

17:53.076 --> 17:53.086 align:start position:0%
with satellites.
 

17:53.086 --> 17:55.356 align:start position:0%
with satellites.
In<00:20:09.480><c> low</c><00:20:09.760><c> Earth's</c><00:20:10.120><c> orbit,</c><00:20:10.720><c> satellites</c><00:20:11.240><c> travel</c>

17:55.356 --> 17:55.366 align:start position:0%
In low Earth's orbit, satellites travel
 

17:55.366 --> 17:58.156 align:start position:0%
In low Earth's orbit, satellites travel
at<00:20:12.000><c> 28,000</c><00:20:12.920><c> km/h.</c>

17:58.156 --> 17:58.166 align:start position:0%
at 28,000 km/h.
 

17:58.166 --> 18:00.236 align:start position:0%
at 28,000 km/h.
At<00:20:14.560><c> this</c><00:20:14.800><c> speed,</c><00:20:15.360><c> even</c><00:20:15.640><c> the</c><00:20:15.760><c> tiniest</c>

18:00.236 --> 18:00.246 align:start position:0%
At this speed, even the tiniest
 

18:00.246 --> 18:02.596 align:start position:0%
At this speed, even the tiniest
particles<00:20:17.120><c> can</c><00:20:17.360><c> wreak</c><00:20:17.720><c> havoc.</c>

18:02.596 --> 18:02.606 align:start position:0%
particles can wreak havoc.
 

18:02.606 --> 18:04.356 align:start position:0%
particles can wreak havoc.
Satellites<00:20:19.400><c> would</c><00:20:19.520><c> need</c><00:20:19.800><c> precise</c><00:20:20.360><c> launch</c>

18:04.356 --> 18:04.366 align:start position:0%
Satellites would need precise launch
 

18:04.366 --> 18:06.236 align:start position:0%
Satellites would need precise launch
windows<00:20:21.080><c> to</c><00:20:21.240><c> thread</c><00:20:21.680><c> through</c><00:20:21.960><c> the</c><00:20:22.080><c> gaps</c><00:20:22.440><c> in</c>

18:06.236 --> 18:06.246 align:start position:0%
windows to thread through the gaps in
 

18:06.246 --> 18:08.556 align:start position:0%
windows to thread through the gaps in
the<00:20:22.640><c> ring,</c><00:20:23.240><c> or</c><00:20:23.760><c> heavy</c><00:20:24.040><c> shielding,</c><00:20:24.640><c> which</c>

18:08.556 --> 18:08.566 align:start position:0%
the ring, or heavy shielding, which
 

18:08.566 --> 18:10.636 align:start position:0%
the ring, or heavy shielding, which
would<00:20:25.120><c> increase</c><00:20:25.560><c> payload</c><00:20:26.000><c> weight</c><00:20:26.440><c> and</c><00:20:26.720><c> lead</c>

18:10.636 --> 18:10.646 align:start position:0%
would increase payload weight and lead
 

18:10.646 --> 18:12.716 align:start position:0%
would increase payload weight and lead
to<00:20:27.040><c> higher</c><00:20:27.440><c> fuel</c><00:20:27.800><c> costs.</c>

18:12.716 --> 18:12.726 align:start position:0%
to higher fuel costs.
 

18:12.726 --> 18:13.996 align:start position:0%
to higher fuel costs.
Maintenance<00:20:29.520><c> would</c><00:20:29.680><c> also</c><00:20:29.960><c> be</c><00:20:30.080><c> more</c>

18:13.996 --> 18:14.006 align:start position:0%
Maintenance would also be more
 

18:14.006 --> 18:15.636 align:start position:0%
Maintenance would also be more
challenging.<00:20:31.200><c> Failure</c><00:20:31.560><c> rates</c><00:20:31.800><c> would</c>

18:15.636 --> 18:15.646 align:start position:0%
challenging. Failure rates would
 

18:15.646 --> 18:17.596 align:start position:0%
challenging. Failure rates would
increase,<00:20:32.760><c> and</c><00:20:32.920><c> the</c><00:20:33.000><c> whole</c><00:20:33.440><c> thing</c><00:20:33.760><c> would</c>

18:17.596 --> 18:17.606 align:start position:0%
increase, and the whole thing would
 

18:17.606 --> 18:20.356 align:start position:0%
increase, and the whole thing would
become<00:20:34.320><c> much</c><00:20:34.760><c> less</c><00:20:35.080><c> reliable.</c>

18:20.356 --> 18:20.366 align:start position:0%
become much less reliable.
 

18:20.366 --> 18:22.036 align:start position:0%
become much less reliable.
Back<00:20:36.840><c> home</c><00:20:37.080><c> on</c><00:20:37.240><c> Earth,</c><00:20:37.600><c> this</c><00:20:37.880><c> would</c><00:20:38.040><c> spell</c>

18:22.036 --> 18:22.046 align:start position:0%
Back home on Earth, this would spell
 

18:22.046 --> 18:24.356 align:start position:0%
Back home on Earth, this would spell
disaster<00:20:38.840><c> for</c><00:20:39.000><c> our</c><00:20:39.120><c> modern</c><00:20:39.400><c> way</c><00:20:39.560><c> of</c><00:20:39.680><c> life.</c>

18:24.356 --> 18:24.366 align:start position:0%
disaster for our modern way of life.
 

18:24.366 --> 18:26.516 align:start position:0%
disaster for our modern way of life.
We<00:20:40.800><c> personally</c><00:20:41.480><c> rely</c><00:20:41.920><c> on</c><00:20:42.080><c> satellites</c><00:20:42.600><c> every</c>

18:26.516 --> 18:26.526 align:start position:0%
We personally rely on satellites every
 

18:26.526 --> 18:28.556 align:start position:0%
We personally rely on satellites every
day<00:20:43.160><c> for</c><00:20:43.520><c> high-speed</c><00:20:44.040><c> internet,</c>

18:28.556 --> 18:28.566 align:start position:0%
day for high-speed internet,
 

18:28.566 --> 18:31.396 align:start position:0%
day for high-speed internet,
telecommunications,<00:20:45.920><c> and</c><00:20:46.240><c> GPS.</c><00:20:47.480><c> But,</c><00:20:47.560><c> we</c>

18:31.396 --> 18:31.406 align:start position:0%
telecommunications, and GPS. But, we
 

18:31.406 --> 18:33.836 align:start position:0%
telecommunications, and GPS. But, we
also<00:20:47.960><c> benefit</c><00:20:48.400><c> from</c><00:20:48.600><c> them</c><00:20:48.920><c> in</c><00:20:49.240><c> more</c><00:20:49.520><c> indirect</c>

18:33.836 --> 18:33.846 align:start position:0%
also benefit from them in more indirect
 

18:33.846 --> 18:36.636 align:start position:0%
also benefit from them in more indirect
ways.<00:20:51.040><c> Aviation</c><00:20:51.760><c> and</c><00:20:52.000><c> shipping</c><00:20:52.320><c> industries</c>

18:36.636 --> 18:36.646 align:start position:0%
ways. Aviation and shipping industries
 

18:36.646 --> 18:39.156 align:start position:0%
ways. Aviation and shipping industries
need<00:20:53.320><c> accurate</c><00:20:53.800><c> GPS</c><00:20:54.360><c> to</c><00:20:54.480><c> keep</c><00:20:54.840><c> operations</c>

18:39.156 --> 18:39.166 align:start position:0%
need accurate GPS to keep operations
 

18:39.166 --> 18:41.316 align:start position:0%
need accurate GPS to keep operations
smooth<00:20:55.840><c> and</c><00:20:55.920><c> efficient,</c><00:20:56.680><c> keeping</c><00:20:57.120><c> the</c><00:20:57.200><c> global</c>

18:41.316 --> 18:41.326 align:start position:0%
smooth and efficient, keeping the global
 

18:41.326 --> 18:43.836 align:start position:0%
smooth and efficient, keeping the global
economy<00:20:58.040><c> running.</c><00:20:58.960><c> Weather</c><00:20:59.240><c> predictions</c><00:20:59.800><c> let</c>

18:43.836 --> 18:43.846 align:start position:0%
economy running. Weather predictions let
 

18:43.846 --> 18:46.116 align:start position:0%
economy running. Weather predictions let
farmers<00:21:00.680><c> manage</c><00:21:01.120><c> their</c><00:21:01.320><c> crops</c><00:21:01.640><c> better,</c>

18:46.116 --> 18:46.126 align:start position:0%
farmers manage their crops better,
 

18:46.126 --> 18:48.996 align:start position:0%
farmers manage their crops better,
keeping<00:21:02.800><c> yields</c><00:21:03.120><c> high</c><00:21:03.640><c> and</c><00:21:03.760><c> prices</c><00:21:04.240><c> low.</c>

18:48.996 --> 18:49.006 align:start position:0%
keeping yields high and prices low.
 

18:49.006 --> 18:51.316 align:start position:0%
keeping yields high and prices low.
Speaking<00:21:05.720><c> of</c><00:21:05.840><c> climate,</c><00:21:06.640><c> a</c><00:21:06.720><c> dense</c><00:21:07.160><c> ring</c><00:21:07.400><c> of</c>

18:51.316 --> 18:51.326 align:start position:0%
Speaking of climate, a dense ring of
 

18:51.326 --> 18:53.196 align:start position:0%
Speaking of climate, a dense ring of
rocks<00:21:07.880><c> surrounding</c><00:21:08.280><c> the</c><00:21:08.360><c> planet</c><00:21:08.760><c> is</c><00:21:09.000><c> bound</c><00:21:09.360><c> to</c>

18:53.196 --> 18:53.206 align:start position:0%
rocks surrounding the planet is bound to
 

18:53.206 --> 18:55.836 align:start position:0%
rocks surrounding the planet is bound to
affect<00:21:09.840><c> it.</c><00:21:10.640><c> The</c><00:21:10.720><c> exact</c><00:21:11.120><c> impact</c><00:21:11.520><c> of</c><00:21:11.640><c> rings</c><00:21:11.920><c> on</c>

18:55.836 --> 18:55.846 align:start position:0%
affect it. The exact impact of rings on
 

18:55.846 --> 18:57.196 align:start position:0%
affect it. The exact impact of rings on
Earth's<00:21:12.320><c> weather</c><00:21:12.560><c> patterns</c><00:21:12.960><c> is</c><00:21:13.120><c> hard</c><00:21:13.400><c> to</c>

18:57.196 --> 18:57.206 align:start position:0%
Earth's weather patterns is hard to
 

18:57.206 --> 18:59.676 align:start position:0%
Earth's weather patterns is hard to
pinpoint,<00:21:14.480><c> but</c><00:21:14.600><c> there</c><00:21:14.880><c> are</c><00:21:15.000><c> a</c><00:21:15.080><c> few</c><00:21:15.400><c> things</c><00:21:15.760><c> we</c>

18:59.676 --> 18:59.686 align:start position:0%
pinpoint, but there are a few things we
 

18:59.686 --> 19:01.436 align:start position:0%
pinpoint, but there are a few things we
are<00:21:16.080><c> fairly</c><00:21:16.560><c> sure</c><00:21:16.880><c> of.</c>

19:01.436 --> 19:01.446 align:start position:0%
are fairly sure of.
 

19:01.446 --> 19:03.156 align:start position:0%
are fairly sure of.
At<00:21:18.000><c> the</c><00:21:18.120><c> equator,</c><00:21:18.520><c> the</c><00:21:18.640><c> rings</c><00:21:18.920><c> would</c><00:21:19.120><c> block</c>

19:03.156 --> 19:03.166 align:start position:0%
At the equator, the rings would block
 

19:03.166 --> 19:05.436 align:start position:0%
At the equator, the rings would block
some<00:21:19.840><c> of</c><00:21:19.960><c> the</c><00:21:20.080><c> incoming</c><00:21:20.480><c> light,</c><00:21:21.200><c> casting</c><00:21:21.680><c> a</c>

19:05.436 --> 19:05.446 align:start position:0%
some of the incoming light, casting a
 

19:05.446 --> 19:08.676 align:start position:0%
some of the incoming light, casting a
shadow<00:21:22.200><c> on</c><00:21:22.440><c> equatorial</c><00:21:23.080><c> regions</c><00:21:23.640><c> like</c><00:21:23.920><c> this.</c>

19:08.676 --> 19:08.686 align:start position:0%
shadow on equatorial regions like this.
 

19:08.686 --> 19:10.236 align:start position:0%
shadow on equatorial regions like this.
As<00:21:25.240><c> the</c><00:21:25.400><c> Earth</c><00:21:25.600><c> rotates</c><00:21:26.160><c> through</c><00:21:26.400><c> the</c>

19:10.236 --> 19:10.246 align:start position:0%
As the Earth rotates through the
 

19:10.246 --> 19:12.876 align:start position:0%
As the Earth rotates through the
seasons,<00:21:27.480><c> different</c><00:21:27.960><c> equatorial</c><00:21:28.640><c> regions</c>

19:12.876 --> 19:12.886 align:start position:0%
seasons, different equatorial regions
 

19:12.886 --> 19:14.836 align:start position:0%
seasons, different equatorial regions
experience<00:21:29.800><c> this</c><00:21:30.000><c> shadow.</c>

19:14.836 --> 19:14.846 align:start position:0%
experience this shadow.
 

19:14.846 --> 19:17.036 align:start position:0%
experience this shadow.
It<00:21:31.400><c> hits</c><00:21:31.760><c> the</c><00:21:32.040><c> southern</c><00:21:32.360><c> tropics</c><00:21:32.760><c> in</c><00:21:32.920><c> June,</c>

19:17.036 --> 19:17.046 align:start position:0%
It hits the southern tropics in June,
 

19:17.046 --> 19:19.276 align:start position:0%
It hits the southern tropics in June,
July,<00:21:33.680><c> and</c><00:21:33.840><c> August,</c><00:21:34.800><c> and</c><00:21:35.000><c> the</c><00:21:35.080><c> northern</c>

19:19.276 --> 19:19.286 align:start position:0%
July, and August, and the northern
 

19:19.286 --> 19:21.156 align:start position:0%
July, and August, and the northern
tropics<00:21:35.960><c> in</c><00:21:36.120><c> December,</c><00:21:36.840><c> January,</c><00:21:37.280><c> and</c>

19:21.156 --> 19:21.166 align:start position:0%
tropics in December, January, and
 

19:21.166 --> 19:23.876 align:start position:0%
tropics in December, January, and
February,<00:21:38.280><c> making</c><00:21:38.640><c> winters</c><00:21:39.120><c> on</c><00:21:39.240><c> both</c><00:21:39.520><c> sides</c>

19:23.876 --> 19:23.886 align:start position:0%
February, making winters on both sides
 

19:23.886 --> 19:25.596 align:start position:0%
February, making winters on both sides
much<00:21:40.480><c> colder.</c>

19:25.596 --> 19:25.606 align:start position:0%
much colder.
 

19:25.606 --> 19:28.076 align:start position:0%
much colder.
During<00:21:42.320><c> equinoxes,</c><00:21:43.120><c> when</c><00:21:43.360><c> the</c><00:21:43.520><c> Earth's</c><00:21:43.880><c> axis</c>

19:28.076 --> 19:28.086 align:start position:0%
During equinoxes, when the Earth's axis
 

19:28.086 --> 19:29.916 align:start position:0%
During equinoxes, when the Earth's axis
tilts<00:21:44.774><c> [music]</c><00:21:44.840><c> neither</c><00:21:45.200><c> towards</c><00:21:45.760><c> or</c><00:21:45.880><c> away</c>

19:29.916 --> 19:29.926 align:start position:0%
tilts [music] neither towards or away
 

19:29.926 --> 19:32.156 align:start position:0%
tilts [music] neither towards or away
from<00:21:46.360><c> the</c><00:21:46.440><c> Sun,</c><00:21:47.040><c> the</c><00:21:47.160><c> shadow</c><00:21:47.520><c> would</c><00:21:47.760><c> fall</c><00:21:48.160><c> in</c><00:21:48.360><c> a</c>

19:32.156 --> 19:32.166 align:start position:0%
from the Sun, the shadow would fall in a
 

19:32.166 --> 19:35.636 align:start position:0%
from the Sun, the shadow would fall in a
thin<00:21:49.000><c> line</c><00:21:49.400><c> directly</c><00:21:50.240><c> on</c><00:21:50.520><c> the</c><00:21:50.640><c> equator.</c>

19:35.636 --> 19:35.646 align:start position:0%
thin line directly on the equator.
 

19:35.646 --> 19:37.436 align:start position:0%
thin line directly on the equator.
The<00:21:52.120><c> cooling</c><00:21:52.520><c> effect</c><00:21:52.960><c> might</c><00:21:53.280><c> only</c><00:21:53.520><c> be</c><00:21:53.680><c> a</c>

19:37.436 --> 19:37.446 align:start position:0%
The cooling effect might only be a
 

19:37.446 --> 19:39.196 align:start position:0%
The cooling effect might only be a
degree<00:21:54.040><c> or</c><00:21:54.160><c> two,</c><00:21:54.760><c> but</c><00:21:54.880><c> that's</c><00:21:55.080><c> enough</c><00:21:55.320><c> to</c>

19:39.196 --> 19:39.206 align:start position:0%
degree or two, but that's enough to
 

19:39.206 --> 19:41.556 align:start position:0%
degree or two, but that's enough to
shift<00:21:55.920><c> weather</c><00:21:56.200><c> patterns,</c><00:21:57.120><c> alter</c><00:21:57.480><c> growing</c>

19:41.556 --> 19:41.566 align:start position:0%
shift weather patterns, alter growing
 

19:41.566 --> 19:43.636 align:start position:0%
shift weather patterns, alter growing
seasons,<00:21:58.400><c> and</c><00:21:58.720><c> stress</c><00:21:59.185><c> [music]</c><00:21:59.200><c> ecosystems</c>

19:43.636 --> 19:43.646 align:start position:0%
seasons, and stress [music] ecosystems
 

19:43.646 --> 19:46.196 align:start position:0%
seasons, and stress [music] ecosystems
that<00:22:00.040><c> depend</c><00:22:00.440><c> on</c><00:22:00.600><c> consistent</c><00:22:01.240><c> sunlight,</c><00:22:02.160><c> just</c>

19:46.196 --> 19:46.206 align:start position:0%
that depend on consistent sunlight, just
 

19:46.206 --> 19:47.836 align:start position:0%
that depend on consistent sunlight, just
as<00:22:02.600><c> it</c><00:22:02.760><c> might</c><00:22:02.960><c> have</c><00:22:03.080><c> done</c><00:22:03.320><c> during</c><00:22:03.560><c> the</c><00:22:03.720><c> late</c>

19:47.836 --> 19:47.846 align:start position:0%
as it might have done during the late
 

19:47.846 --> 19:49.956 align:start position:0%
as it might have done during the late
Ordovician<00:22:04.760><c> mass</c><00:22:05.040><c> extinction</c><00:22:05.800><c> I</c><00:22:05.840><c> mentioned</c>

19:49.956 --> 19:49.966 align:start position:0%
Ordovician mass extinction I mentioned
 

19:49.966 --> 19:51.116 align:start position:0%
Ordovician mass extinction I mentioned
earlier.

19:51.116 --> 19:51.126 align:start position:0%
earlier.
 

19:51.126 --> 19:53.756 align:start position:0%
earlier.
At<00:22:07.760><c> the</c><00:22:08.000><c> middle</c><00:22:08.360><c> latitudes,</c><00:22:09.320><c> the</c><00:22:09.440><c> equinox</c>

19:53.756 --> 19:53.766 align:start position:0%
At the middle latitudes, the equinox
 

19:53.766 --> 19:56.076 align:start position:0%
At the middle latitudes, the equinox
looks<00:22:10.360><c> completely</c><00:22:10.880><c> different.</c><00:22:11.960><c> The</c><00:22:12.040><c> planet</c>

19:56.076 --> 19:56.086 align:start position:0%
looks completely different. The planet
 

19:56.086 --> 19:58.556 align:start position:0%
looks completely different. The planet
silhouette<00:22:12.960><c> stretches</c><00:22:13.520><c> across</c><00:22:13.920><c> the</c><00:22:14.040><c> rings,</c>

19:58.556 --> 19:58.566 align:start position:0%
silhouette stretches across the rings,
 

19:58.566 --> 20:01.476 align:start position:0%
silhouette stretches across the rings,
casting<00:22:15.360><c> the</c><00:22:15.640><c> largest</c><00:22:16.360><c> shadow</c><00:22:16.720><c> of</c><00:22:16.840><c> the</c><00:22:16.960><c> year,</c>

20:01.476 --> 20:01.486 align:start position:0%
casting the largest shadow of the year,
 

20:01.486 --> 20:03.316 align:start position:0%
casting the largest shadow of the year,
the<00:22:17.880><c> smallest</c><00:22:18.840><c> then</c><00:22:19.000><c> arriving</c><00:22:19.440><c> at</c><00:22:19.520><c> the</c>

20:03.316 --> 20:03.326 align:start position:0%
the smallest then arriving at the
 

20:03.326 --> 20:06.036 align:start position:0%
the smallest then arriving at the
solstice.<00:22:20.760><c> Imagine</c><00:22:21.280><c> the</c><00:22:21.360><c> kind</c><00:22:21.680><c> of</c><00:22:21.800><c> folklore</c>

20:06.036 --> 20:06.046 align:start position:0%
solstice. Imagine the kind of folklore
 

20:06.046 --> 20:07.876 align:start position:0%
solstice. Imagine the kind of folklore
that<00:22:22.480><c> would</c><00:22:22.640><c> arise</c><00:22:23.160><c> from</c><00:22:23.360><c> witnessing</c><00:22:23.920><c> such</c>

20:07.876 --> 20:07.886 align:start position:0%
that would arise from witnessing such
 

20:07.886 --> 20:10.996 align:start position:0%
that would arise from witnessing such
phenomena<00:22:25.040><c> year</c><00:22:25.560><c> after</c><00:22:25.920><c> year.</c>

20:10.996 --> 20:11.006 align:start position:0%
phenomena year after year.
 

20:11.006 --> 20:12.676 align:start position:0%
phenomena year after year.
But<00:22:27.520><c> perhaps</c><00:22:27.880><c> the</c><00:22:27.960><c> most</c><00:22:28.280><c> imminent</c><00:22:28.600><c> threat</c><00:22:28.880><c> to</c>

20:12.676 --> 20:12.686 align:start position:0%
But perhaps the most imminent threat to
 

20:12.686 --> 20:14.956 align:start position:0%
But perhaps the most imminent threat to
civilization<00:22:29.720><c> on</c><00:22:29.920><c> a</c><00:22:30.000><c> ringed</c><00:22:30.440><c> Earth</c><00:22:30.800><c> would</c><00:22:31.040><c> be</c>

20:14.956 --> 20:14.966 align:start position:0%
civilization on a ringed Earth would be
 

20:14.966 --> 20:17.756 align:start position:0%
civilization on a ringed Earth would be
the<00:22:31.480><c> infall</c><00:22:32.120><c> from</c><00:22:32.360><c> the</c><00:22:32.480><c> rings</c><00:22:32.800><c> themselves.</c>

20:17.756 --> 20:17.766 align:start position:0%
the infall from the rings themselves.
 

20:17.766 --> 20:20.476 align:start position:0%
the infall from the rings themselves.
Most<00:22:34.560><c> would</c><00:22:34.840><c> burn</c><00:22:35.120><c> up</c><00:22:35.240><c> as</c><00:22:35.400><c> meteors,</c><00:22:36.400><c> setting</c>

20:20.476 --> 20:20.486 align:start position:0%
Most would burn up as meteors, setting
 

20:20.486 --> 20:22.596 align:start position:0%
Most would burn up as meteors, setting
the<00:22:36.840><c> sky</c><00:22:37.160><c> ablaze</c><00:22:37.680><c> for</c><00:22:37.800><c> those</c><00:22:38.120><c> near</c><00:22:38.400><c> enough</c><00:22:38.760><c> the</c>

20:22.596 --> 20:22.606 align:start position:0%
the sky ablaze for those near enough the
 

20:22.606 --> 20:24.236 align:start position:0%
the sky ablaze for those near enough the
equator<00:22:39.280><c> to</c><00:22:39.400><c> see</c><00:22:39.640><c> it.</c>

20:24.236 --> 20:24.246 align:start position:0%
equator to see it.
 

20:24.246 --> 20:26.076 align:start position:0%
equator to see it.
But<00:22:40.680><c> every</c><00:22:40.920><c> now</c><00:22:41.200><c> and</c><00:22:41.320><c> then,</c><00:22:41.720><c> a</c><00:22:41.880><c> larger</c>

20:26.076 --> 20:26.086 align:start position:0%
But every now and then, a larger
 

20:26.086 --> 20:28.076 align:start position:0%
But every now and then, a larger
fragment<00:22:42.840><c> would</c><00:22:43.000><c> get</c><00:22:43.200><c> past</c><00:22:43.640><c> our</c><00:22:43.840><c> atmospheric</c>

20:28.076 --> 20:28.086 align:start position:0%
fragment would get past our atmospheric
 

20:28.086 --> 20:30.956 align:start position:0%
fragment would get past our atmospheric
defense<00:22:45.040><c> and</c><00:22:45.160><c> collide</c><00:22:45.680><c> with</c><00:22:45.800><c> the</c><00:22:45.880><c> planet.</c>

20:30.956 --> 20:30.966 align:start position:0%
defense and collide with the planet.
 

20:30.966 --> 20:33.396 align:start position:0%
defense and collide with the planet.
Now,<00:22:47.720><c> we</c><00:22:47.840><c> can't</c><00:22:48.280><c> know</c><00:22:48.520><c> how</c><00:22:48.760><c> big</c><00:22:49.080><c> the</c><00:22:49.160><c> debris</c><00:22:49.560><c> in</c>

20:33.396 --> 20:33.406 align:start position:0%
Now, we can't know how big the debris in
 

20:33.406 --> 20:35.396 align:start position:0%
Now, we can't know how big the debris in
our<00:22:49.800><c> ring</c><00:22:50.080><c> system</c><00:22:50.440><c> would</c><00:22:50.560><c> have</c><00:22:50.680><c> been,</c><00:22:51.480><c> but</c><00:22:51.600><c> a</c>

20:35.396 --> 20:35.406 align:start position:0%
our ring system would have been, but a
 

20:35.406 --> 20:38.676 align:start position:0%
our ring system would have been, but a
fragment<00:22:52.280><c> only</c><00:22:52.600><c> has</c><00:22:52.840><c> to</c><00:22:52.920><c> be</c><00:22:53.120><c> 50</c><00:22:53.600><c> m</c><00:22:53.960><c> wide</c><00:22:54.880><c> to</c>

20:38.676 --> 20:38.686 align:start position:0%
fragment only has to be 50 m wide to
 

20:38.686 --> 20:41.476 align:start position:0%
fragment only has to be 50 m wide to
destroy<00:22:55.520><c> an</c><00:22:55.680><c> entire</c><00:22:56.240><c> city.</c><00:22:57.240><c> That</c><00:22:57.480><c> doesn't</c>

20:41.476 --> 20:41.486 align:start position:0%
destroy an entire city. That doesn't
 

20:41.486 --> 20:43.076 align:start position:0%
destroy an entire city. That doesn't
mean<00:22:57.880><c> that</c><00:22:58.040><c> those</c><00:22:58.440><c> living</c><00:22:58.760><c> closer</c><00:22:59.120><c> to</c><00:22:59.240><c> the</c>

20:43.076 --> 20:43.086 align:start position:0%
mean that those living closer to the
 

20:43.086 --> 20:45.396 align:start position:0%
mean that those living closer to the
poles<00:22:59.720><c> are</c><00:22:59.880><c> safe</c><00:23:00.160><c> from</c><00:23:00.320><c> catastrophe.</c>

20:45.396 --> 20:45.406 align:start position:0%
poles are safe from catastrophe.
 

20:45.406 --> 20:49.036 align:start position:0%
poles are safe from catastrophe.
A<00:23:01.760><c> rock</c><00:23:02.065><c> [music]</c><00:23:02.120><c> just</c><00:23:02.560><c> 1</c><00:23:03.040><c> km</c><00:23:03.680><c> wide</c><00:23:04.520><c> can</c><00:23:04.720><c> spell</c>

20:49.036 --> 20:49.046 align:start position:0%
A rock [music] just 1 km wide can spell
 

20:49.046 --> 20:51.476 align:start position:0%
A rock [music] just 1 km wide can spell
global<00:23:05.960><c> devastation.</c>

20:51.476 --> 20:51.486 align:start position:0%
global devastation.
 

20:51.486 --> 20:53.556 align:start position:0%
global devastation.
But<00:23:07.880><c> perhaps</c><00:23:08.320><c> my</c><00:23:08.560><c> favorite</c><00:23:09.080><c> difference</c><00:23:09.680><c> in</c>

20:53.556 --> 20:53.566 align:start position:0%
But perhaps my favorite difference in
 

20:53.566 --> 20:56.116 align:start position:0%
But perhaps my favorite difference in
this<00:23:10.040><c> ringed</c><00:23:10.360><c> world</c><00:23:10.840><c> would</c><00:23:11.000><c> be</c><00:23:11.240><c> how</c><00:23:11.680><c> we</c><00:23:11.840><c> study</c>

20:56.116 --> 20:56.126 align:start position:0%
this ringed world would be how we study
 

20:56.126 --> 20:59.716 align:start position:0%
this ringed world would be how we study
and<00:23:12.640><c> understand</c><00:23:13.240><c> our</c><00:23:13.520><c> own</c><00:23:14.040><c> cosmic</c><00:23:14.440><c> backyard.</c>

20:59.716 --> 20:59.726 align:start position:0%
and understand our own cosmic backyard.
 

20:59.726 --> 21:01.436 align:start position:0%
and understand our own cosmic backyard.
Mission<00:23:16.320><c> launches</c><00:23:16.800><c> would</c><00:23:17.000><c> face</c><00:23:17.320><c> the</c><00:23:17.440><c> same</c>

21:01.436 --> 21:01.446 align:start position:0%
Mission launches would face the same
 

21:01.446 --> 21:03.476 align:start position:0%
Mission launches would face the same
challenges<00:23:18.400><c> as</c><00:23:18.560><c> satellites.</c>

21:03.476 --> 21:03.486 align:start position:0%
challenges as satellites.
 

21:03.486 --> 21:05.076 align:start position:0%
challenges as satellites.
And<00:23:19.880><c> even</c><00:23:20.080><c> if</c><00:23:20.200><c> we</c><00:23:20.320><c> could</c><00:23:20.600><c> successfully</c><00:23:21.200><c> pull</c>

21:05.076 --> 21:05.086 align:start position:0%
And even if we could successfully pull
 

21:05.086 --> 21:07.436 align:start position:0%
And even if we could successfully pull
it<00:23:21.520><c> off,</c><00:23:22.080><c> the</c><00:23:22.240><c> ring</c><00:23:22.640><c> would</c><00:23:22.840><c> interfere</c><00:23:23.360><c> with</c>

21:07.436 --> 21:07.446 align:start position:0%
it off, the ring would interfere with
 

21:07.446 --> 21:09.756 align:start position:0%
it off, the ring would interfere with
radio<00:23:24.120><c> communication,</c><00:23:25.360><c> scattering</c>

21:09.756 --> 21:09.766 align:start position:0%
radio communication, scattering
 

21:09.766 --> 21:12.637 align:start position:0%
radio communication, scattering
transmissions,<00:23:26.880><c> and</c><00:23:27.120><c> creating</c><00:23:27.760><c> dead</c><00:23:28.040><c> zones.</c>

21:12.637 --> 21:12.647 align:start position:0%
transmissions, and creating dead zones.
 

21:12.647 --> 21:12.836 align:start position:0%
transmissions, and creating dead zones.
&gt;&gt; [music]

21:12.836 --> 21:12.846 align:start position:0%
&gt;&gt; [music]
 

21:12.846 --> 21:14.956 align:start position:0%
&gt;&gt; [music]
&gt;&gt; Any<00:23:29.400><c> probe</c><00:23:30.040><c> we</c><00:23:30.200><c> send</c><00:23:30.560><c> to</c><00:23:30.720><c> far-flung</c>

21:14.956 --> 21:14.966 align:start position:0%
&gt;&gt; Any probe we send to far-flung
 

21:14.966 --> 21:17.476 align:start position:0%
&gt;&gt; Any probe we send to far-flung
destinations<00:23:32.040><c> would</c><00:23:32.240><c> ping</c><00:23:32.600><c> back</c><00:23:32.960><c> distorted</c>

21:17.476 --> 21:17.486 align:start position:0%
destinations would ping back distorted
 

21:17.486 --> 21:18.636 align:start position:0%
destinations would ping back distorted
signals.

21:18.636 --> 21:18.646 align:start position:0%
signals.
 

21:18.646 --> 21:20.996 align:start position:0%
signals.
Radio<00:23:35.280><c> astronomy,</c><00:23:36.160><c> critical</c><00:23:36.720><c> for</c><00:23:36.840><c> studying</c>

21:20.996 --> 21:21.006 align:start position:0%
Radio astronomy, critical for studying
 

21:21.006 --> 21:22.876 align:start position:0%
Radio astronomy, critical for studying
black<00:23:37.640><c> holes,</c><00:23:38.160><c> pulsars,</c><00:23:38.760><c> and</c><00:23:38.880><c> distant</c>

21:22.876 --> 21:22.886 align:start position:0%
black holes, pulsars, and distant
 

21:22.886 --> 21:24.996 align:start position:0%
black holes, pulsars, and distant
galaxies,<00:23:40.240><c> would</c><00:23:40.360><c> get</c><00:23:40.600><c> muddled</c><00:23:41.080><c> with</c>

21:24.996 --> 21:25.006 align:start position:0%
galaxies, would get muddled with
 

21:25.006 --> 21:26.996 align:start position:0%
galaxies, would get muddled with
interference,<00:23:42.120><c> especially</c><00:23:42.840><c> around</c><00:23:43.160><c> the</c>

21:26.996 --> 21:27.006 align:start position:0%
interference, especially around the
 

21:27.006 --> 21:28.516 align:start position:0%
interference, especially around the
equator.

21:28.516 --> 21:28.526 align:start position:0%
equator.
 

21:28.526 --> 21:30.316 align:start position:0%
equator.
Ground-based<00:23:45.440><c> astronomy</c><00:23:45.880><c> would</c><00:23:46.080><c> also</c><00:23:46.360><c> take</c><00:23:46.560><c> a</c>

21:30.316 --> 21:30.326 align:start position:0%
Ground-based astronomy would also take a
 

21:30.326 --> 21:32.356 align:start position:0%
Ground-based astronomy would also take a
hit.<00:23:47.240><c> The</c><00:23:47.360><c> light</c><00:23:47.640><c> scattering</c><00:23:48.080><c> off</c><00:23:48.240><c> the</c><00:23:48.320><c> rings</c>

21:32.356 --> 21:32.366 align:start position:0%
hit. The light scattering off the rings
 

21:32.366 --> 21:34.716 align:start position:0%
hit. The light scattering off the rings
would<00:23:48.800><c> make</c><00:23:49.200><c> faint</c><00:23:49.560><c> objects</c><00:23:50.040><c> even</c><00:23:50.400><c> harder</c><00:23:50.880><c> to</c>

21:34.716 --> 21:34.726 align:start position:0%
would make faint objects even harder to
 

21:34.726 --> 21:37.196 align:start position:0%
would make faint objects even harder to
detect.<00:23:52.160><c> Our</c><00:23:52.320><c> view</c><00:23:52.640><c> outward</c><00:23:53.160><c> into</c><00:23:53.400><c> the</c>

21:37.196 --> 21:37.206 align:start position:0%
detect. Our view outward into the
 

21:37.206 --> 21:39.476 align:start position:0%
detect. Our view outward into the
universe<00:23:54.000><c> would</c><00:23:54.120><c> be</c><00:23:54.280><c> compromised.</c>

21:39.476 --> 21:39.486 align:start position:0%
universe would be compromised.
 

21:39.486 --> 21:41.516 align:start position:0%
universe would be compromised.
The<00:23:55.880><c> sky</c><00:23:56.200><c> would</c><00:23:56.440><c> be</c><00:23:56.600><c> more</c><00:23:56.960><c> awe-inspiring,</c>

21:41.516 --> 21:41.526 align:start position:0%
The sky would be more awe-inspiring,
 

21:41.526 --> 21:42.476 align:start position:0%
The sky would be more awe-inspiring,
yes,

21:42.476 --> 21:42.486 align:start position:0%
yes,
 

21:42.486 --> 21:45.396 align:start position:0%
yes,
but<00:23:58.880><c> it</c><00:23:58.960><c> would</c><00:23:59.080><c> be</c><00:23:59.240><c> much</c><00:23:59.680><c> harder</c><00:24:00.160><c> to</c><00:24:00.280><c> study.</c>

21:45.396 --> 21:45.406 align:start position:0%
but it would be much harder to study.
 

21:45.406 --> 21:47.236 align:start position:0%
but it would be much harder to study.
Just<00:24:01.880><c> because</c><00:24:02.360><c> Earth</c><00:24:02.720><c> doesn't</c><00:24:03.040><c> currently</c>

21:47.236 --> 21:47.246 align:start position:0%
Just because Earth doesn't currently
 

21:47.246 --> 21:49.636 align:start position:0%
Just because Earth doesn't currently
have<00:24:03.800><c> rings,</c><00:24:04.440><c> doesn't</c><00:24:04.760><c> mean</c><00:24:05.280><c> it</c><00:24:05.480><c> never</c><00:24:05.760><c> will</c>

21:49.636 --> 21:49.646 align:start position:0%
have rings, doesn't mean it never will
 

21:49.646 --> 21:50.836 align:start position:0%
have rings, doesn't mean it never will
again.

21:50.836 --> 21:50.846 align:start position:0%
again.
 

21:50.846 --> 21:52.716 align:start position:0%
again.
Tompkins<00:24:07.680><c> believes</c><00:24:08.080><c> it's</c><00:24:08.280><c> only</c><00:24:08.520><c> a</c><00:24:08.600><c> matter</c><00:24:08.880><c> of</c>

21:52.716 --> 21:52.726 align:start position:0%
Tompkins believes it's only a matter of
 

21:52.726 --> 21:54.956 align:start position:0%
Tompkins believes it's only a matter of
time<00:24:09.440><c> before</c><00:24:09.720><c> they</c><00:24:09.840><c> return.</c>

21:54.956 --> 21:54.966 align:start position:0%
time before they return.
 

21:54.966 --> 21:57.196 align:start position:0%
time before they return.
But<00:24:11.360><c> when</c><00:24:11.520><c> they</c><00:24:11.640><c> do,</c><00:24:12.320><c> humans</c><00:24:12.640><c> will</c><00:24:12.760><c> adapt,</c><00:24:13.320><c> as</c>

21:57.196 --> 21:57.206 align:start position:0%
But when they do, humans will adapt, as
 

21:57.206 --> 21:58.676 align:start position:0%
But when they do, humans will adapt, as
we<00:24:13.680><c> always</c><00:24:14.000><c> do.</c>

21:58.676 --> 21:58.686 align:start position:0%
we always do.
 

21:58.686 --> 22:00.876 align:start position:0%
we always do.
You<00:24:15.080><c> and</c><00:24:15.240><c> I</c><00:24:15.480><c> won't</c><00:24:15.680><c> be</c><00:24:15.800><c> there</c><00:24:16.000><c> to</c><00:24:16.120><c> see</c><00:24:16.280><c> it.</c>

22:00.876 --> 22:00.886 align:start position:0%
You and I won't be there to see it.
 

22:00.886 --> 22:02.596 align:start position:0%
You and I won't be there to see it.
But<00:24:17.520><c> maybe</c><00:24:17.840><c> that's</c><00:24:18.080><c> what</c><00:24:18.240><c> makes</c><00:24:18.480><c> science</c><00:24:18.760><c> so</c>

22:02.596 --> 22:02.606 align:start position:0%
But maybe that's what makes science so
 

22:02.606 --> 22:05.236 align:start position:0%
But maybe that's what makes science so
powerful.<00:24:20.040><c> It</c><00:24:20.120><c> lets</c><00:24:20.360><c> us</c><00:24:20.520><c> witness</c><00:24:21.080><c> the</c><00:24:21.200><c> wonders</c>

22:05.236 --> 22:05.246 align:start position:0%
powerful. It lets us witness the wonders
 

22:05.246 --> 22:08.276 align:start position:0%
powerful. It lets us witness the wonders
of<00:24:21.640><c> the</c><00:24:21.720><c> universe</c><00:24:22.360><c> across</c><00:24:23.000><c> time,</c><00:24:24.040><c> painting</c>

22:08.276 --> 22:08.286 align:start position:0%
of the universe across time, painting
 

22:08.286 --> 22:10.836 align:start position:0%
of the universe across time, painting
pictures<00:24:25.080><c> of</c><00:24:25.240><c> worlds</c><00:24:25.680><c> we'll</c><00:24:25.840><c> never</c><00:24:26.160><c> touch,</c>

22:10.836 --> 22:10.846 align:start position:0%
pictures of worlds we'll never touch,
 

22:10.846 --> 22:17.956 align:start position:0%
pictures of worlds we'll never touch,
but<00:24:27.280><c> can</c><00:24:27.400><c> still</c><00:24:27.840><c> imagine</c><00:24:28.680><c> and</c><00:24:29.240><c> understand.</c>

22:15.009 --> 22:15.019 align:start position:0%
long-term, and every new member makes it
 

22:15.019 --> 22:17.619 align:start position:0%
long-term, and every new member makes it
stronger.