Two years ago, something strange started
happening to our sun. It started
unleashing gargantuan geomagnetic storms
no one was prepared for. Auroras were
seen as far south as Florida and the
Bahamas, the most powerful recorded in
500 years. And satellites stopped
working. But this wasn't a glitch in the
matrix. our sun was entering its most
active and fiery phase, the solar
maximum. This particular solar maximum,
however, was almost twice as strong as
scientists predicted, and we've been
scrambling to understand why ever since.
What we found has shaken some of our
most fundamental assumptions about the
sun, where its magnetic engine lives,
how accurately we've been measuring it,
and what's actually happening at its
poles. So, what's really going on inside
our star? I'm Alex Mccoan and you're
watching Astramm. Join me as we explore
why solar cycle 25 caught us completely
offguard. How getting closer to the sun
than ever before led to modelbreaking
discoveries and why the next big solar
storm could spell disaster for us here
on Earth.
Every 11 years, the sun goes through a
solar cycle. fluctuating between a calm
dormant period known as the solar
minimum and an explosive fiery period,
the solar maximum. Usually, we can tell
where in its cycle our sun is based on
how many sunspots appear on its surface
with numbers rising and falling
alongside magnetic activity. More
magnetic activity means more sunspots,
which also then leads to more frequent
solar flares and chronal mass ejections.
In other words, solar storms. But for
the last few years, our star has been
acting a bit weird. In 2020, the sun
entered solar cycle 25, which turned out
to be significantly more violent and
turbulent than anyone expected. At its
peak, 216 sunspots were observed in
August 2024 alone, almost double initial
predictions and the highest number in 23
years.
The milliondoll question is why? To
predict how strong a solar cycle could
be, scientists rely on something called
the polar field precursor. Here's how it
works. As sunspots decay over the course
of each cycle, their residual magnetic
flux drifts towards the poles, slowly
building up a strong, coherent magnetic
field there. That polar field at solar
minimum is where the next cycle's
activity comes from. To measure it,
scientists rely on instruments like
NASA's helioismic and magnetic imager,
the HMI, an instrument aboard the Solar
Dynamics Observatory, which has been
observing the sun from Earth's orbit and
sending back countless spectacular
images since 2010.
So, if you can measure the sun's polar
fields accurately, you can predict how
strong the next solar cycle is going to
be. The method isn't perfect, but it's
the most reliable forecasting method we
have. In 2019, an international panel of
experts convened by NASA and Noah
reviewed multiple separate forecasts
based on the previous cycle's minimum
and concluded cycle 25 would peak at 115
sunspots, a weak, unremarkable,
what you might call below average solar
maximum. Cycles 22, 23, and 24 were each
weaker than the last, with cycle 24
being the weakest in the last 100 years.
So, such a prediction didn't seem out of
place. But all that changed with a
shocking realization in 2025.
By building a virtual model of the HMI
and running synthetic magnetic field
data through it, researchers at the
National Solar Observatory discovered
the real HMI had only been detecting
about half of the sun's true magnetic
field strength at the poles. If this is
true, it's no wonder our predictions
were off by a long shot. But solar cycle
25 still came in far stronger than it
should have, suggesting something deeper
was at play.
Since the time of Galileo, scientists
have been trying to understand what
drives solar activity. Our leading
theory places the answer more than
200,000 km below the surface at a
boundary layer called the tacoline. The
core idea was that differential rotation
at the taco wound up magnetic field
lines like coiled springs generating the
dynamo that drives everything we see on
the sun's surface. But in 2024,
researchers from MIT, Northwestern,
Edinburgh, and elsewhere challenged that
assumption. By using a NASA supercomput,
they ran the most detailed solar
simulations ever attempted and found
that the sun's magnetic dynamo actually
originates just 32,000 km below the
surface. Why does this matter? Well, if
this is truly the case, a near surface
dynamo would be driven by magneetto
rotational instability, a phenomenon
that occurs when a weak magnetic field
connects two layers of plasma rotating
at different speeds. Instead of
stabilizing them, it amplifies the
difference, driving turbulence that
generates and sustains the magnetic
dynamo. Such a mechanism could explain
why consecutive solar cycles can
sometimes vary so much in strength and
would produce clear predictions that can
actually be tested unlike the old taco
climb models which relied on poorly
constrained assumptions
and tested them. We have in 2018 NASA
launched the Parker Solar Probe which
among its mission aims was to study the
solar dynamo firsthand.
After a nearly 3-year voyage, it finally
arrived in April 2021, just as the sun
began ramping up towards its maximum.
What it's seen since then from within
the solar atmosphere itself has
transformed our understanding of the
sun's active phase. On Christmas Eve
2024, the Parker Solar Probe made its
closest ever approach to the sun,
capturing both the corona and solar wind
streaming out of it about 6 million km
above the surface, careening past at
almost 700,000 kmh. It's the fastest
human-made object in history.
But these headlines aren't even the most
impressive aspects about it. Over the
course of 27 orbits, the Parker probe
slowly pieced together data that might
have solved a decades old mystery about
our sun's outermost atmosphere.
The sun's surface is a roasting 5,500°.
But the gaseous outermost layer of his
atmosphere, the corona, is significantly
hotter, ranging from 1 million° C to a
mindmelting 10 million° in some regions.
The problem was no one really knew why.
We understood magnetism had something to
do with it, but the picture was fuzzy.
We've long known that magnetic fields
accumulate, concentrate, and strengthen
at the boundaries between convective
cells called super granules. And when
they get powerful enough, these fields
can interact with solar plasma to launch
jets and nanoflares. In areas where the
fields are especially strong, they can
tear through the sun's surface entirely,
producing sunspots and giant magnetic
loops. For the most part, these loops
are closed with both ends attached to
the sun. However, in some places, the
loops are ripped open, extending to the
edge of the heliosphere. These are known
as open magnetic fields. In 1988, Eugene
Parker, an astrophysicist at the
University of Chicago, proposed a
radical new idea. He argued that perhaps
the churning convective super granules
on the surface of the sun could not only
open and close magnetic fields that
stretched into the corona, but could
tangle them. This would build up
magnetic energy in the solar atmosphere
until the field lines buckle, snap, and
reconnect, transferring that stored
energy into the solar atmosphere as
heat.
For the most part, he was ridiculed by
his contemporaries and his theory was
dismissed. But it wouldn't be long
before a probe bearing his name would
kiss the sun. And what it found
vindicated his work beyond his wildest
dreams. Still, even into the dawn of the
21st century, our son's magnetism kept
behaving in surprising, unexplainable
ways. Data from ISSa's SOHO mission
showed us that the solar magnetic field
was much more variable than we thought,
and the solar wind readings taken near
Earth didn't make sense. The particles
showed strange compositional patterns
that were inconsistent with the
prevailing theory of the time that said
solar wind emanated from the sun's
surface. Now, in the last few years, the
Parker Solar Probe has helped us connect
the dots between these seemingly
disparate observations.
Data collected by its whisper camera has
revealed that while the solar wind
appears like a turbulent fluid from near
Earth, from up close, it seems to flow
outward in individual streamlets that
mirror the sizes of the super granules
on the sun's surface. With every orbit,
the probe took a closer look at these
streams of particles whooshing out from
the sun and found something rather
peculiar. The streamlet showed the
telltale signs of magnetic activity. But
in the field lines, they formed a
strange sshaped structure called
switchbacks. These phenomena are thought
to occur when closed magnetic loops
crash into and connect with open
magnetic loops in what is known as an
interchange reconnection event. These
events generate heat and eject solar
material into space, warming the corona
and accelerating particles in the solar
wind. A concept not that far off from
what Eugene Parker described almost 40
years ago. Now, until recently, our
model of coronal mass ejections assumed
material traveled in one direction from
the sun outward. However, during the
December 2024 flyby, the Parker probe
captured something else. You see this? A
cloud of solar material bursts out from
our star before curling inward and
falling back in a Uturn formation.
According to NASA, the material that
makes it back to the sun can change the
solar atmosphere in subtle but important
ways, which can influence how subsequent
CMEs erupt. Even though we've seen hints
of these inflows before through the SOHO
and stereo missions, we've never seen
this process in such high resolution.
With this data, scientists will be able
to make precise measurements about these
inflows like their speed, shape, and
size, which will ultimately help us
better understand and predict solar
cycles and space weather events, which
could impact astronauts in space as well
as the rest of us here on Earth. We'll
get back to that in a bit. But Parker
has shown us the sun from the inside
out. How its magnetic energy builds,
erupts, and ultimately resets, governing
the 11-year solar cycle. But its orbit
generally keeps it in line with the
sun's equatorial plane. To truly
understand solar cycles, we need to get
a closer look at the hubs of the sun's
magnetic activity. And for that, we're
venturing to the poles.
Now, most spacecraft orbit in the
ecliptic plane, the flat disc traced by
the planets around the sun. This means
that for the entire history of space
exploration, we've only ever seen the
sun's poles edge on, like trying to read
a clock face from the side.
Solar orbiter was designed to fix that.
Using a series of Venus gravity assists
to gradually tilt its orbit, it has been
climbing toward a higher and higher
solar latitude with every pass. On the
23rd of March, 2025, it finally crossed
17° below the solar equator, locked its
instruments on the sun's south pole, and
snapped the first images we've ever
captured of it.
And it turns out the South Pole is a
crazy messy place hiding three big
surprises we're only just beginning to
understand. A normal magnet has clear
north and south polarity. But Solar
Orbiter revealed that for a short time
during the solar maximum, both north and
south polarity magnetic fields are
present at the south pole at the same
time, tangled and intermixed.
To emerge from this bubbling chaos, the
sun flips its entire magnetic field. The
north pole becomes the south and vice
versa. It's a cycle that repeats every
11 years, meaning it takes the sun 22
years to complete an entire magnetic
cycle, also known as the hail cycle.
Once the magnetic field flips, a single
polarity would slowly build up and take
over at the sun's poles, settling into
its most orderly configuration during
the solar minimum when the sun is least
active. Yet, this was just the beginning
of the story. The Solar Orbiter's
onboard spectrometer, the spectral
imaging of the coronal environment
instrument or SPICE, mapped how fast
clumps of solar material were moving
around the transition region of the
polar atmosphere, a thin, irregular
layer of the sun's atmosphere, where
temperatures rapidly increase from
10,000° C to hundreds of thousands of
degrees. SPICE captures the light
different elements like oxygen, neon,
carbon, and hydrogen emit at specific
temperatures and then tracks their
movement to create a velocity map of the
South Pole. These measurements can then
show how particles are flung out from
the sun in the form of solar wind and
represent the first time we've ever
traced solar wind to its source rather
than inferring it from measurements
taken millions of kilometers downstream.
Now, the third and final finding ties
back to solar cycle 25 and why it was so
much stronger than anticipated.
In a November 2025 paper, solar orbiter
data showed the migration of sunspot
magnetic fields towards the poles might
have been happening much faster than we
expected. This has huge implications for
forecasting future solar cycles.
Remember the polar field precursor? The
speed and strength of one's cycle's
poleward drift determines the polar
field strength at the next solar
minimum, which in turn determines the
strength of the next solar cycle. If the
magnetic flux is arriving at the poles
faster than our models predict, our
estimates of future cycles are way off
before we even started. To summarize, it
seems we may have underestimated solar
cycle 25 for a few reasons. Our dynamo
model was flawed. Our instruments only
detected a fraction of the sun's actual
magnetism, and the rate of flux at the
poles is potentially higher than we
thought. Luckily, no massive solar
flares or CMEs came our way. But if they
did, what would that mean for us? Just
how devastating would a massive
geomagnetic storm be for us here on
Earth or our astronauts in space? How
can we prepare for one?
On the 10th of May 2024, a huge
geomagnetic storm struck Earth. These
happen when the sun releases a CME
hurling a billion tons of magnetized
plasma towards our planet. It can take
this material several days to arrive,
but once it does, it slams into Earth's
magneettosphere, triggering a rapid and
often violent exchange of energy between
the solar wind and the space environment
around us. Aurora blazed as far south as
the Florida Keys, the Yucatan Peninsula
in Mexico, the Bahamas, Jamaica, Puerto
Rico, and Hawaii.
Just a month later, the sky turned
faintly red in Japan with an aurora that
scientists have since found stretched
far higher into Earth's atmosphere than
we expected, as high as 800 m. A sign
that charged particles may carry more
energy than we initially thought. But
despite the breathtaking light show,
geomagnetic storms can also be very
dangerous because they affect Earth's
magneettosphere. See, our planet is
surrounded by a plasmosphere, a bubble
of charged plasma that helps deflect
oncoming solar material. When a
geomagnetic storm hits, the pressure
from the solar wind squeezes the
plasmosphere inward, compressing towards
Earth like a deflating balloon. After
the storm passes, the plasmosphere is
replenished by charged particles from
the ionosphere below, which is filled
with ions created when the sun's
radiation strips particles in our upper
atmosphere of electrons. The May 2024
geomagnetic storm as part of cycle 25
solar maximum was the strongest in the
last 21 years. Lucky for us, Jax's array
satellite happened to be in the right
place at the right time to capture its
effects on our protected magneettosphere
like never before. A team led by Dr.
Atsuki Shimbori of Nagoya University's
Institute for Space Earth Environmental
Research collected the first continuous
direct readings of the plasmosphere
collapsing to low altitude during a
supertorrm. The team watched the outer
boundary of the plasmosphere collapse
from 44,000 km down to just 9,600 km in
under 9 hours, roughly 15th of its usual
size. This was the lowest altitude ever
recorded for the plasmosphere's outer
edge in the entire Arz mission era,
which began in 2017. And this
compression left all satellites in
geostationary orbit and most in medium
earth orbit altitude severely exposed to
the full force of the storm. These
include most of our weather monitoring,
TV broadcasting, communication
satellites, and our global navigation
satellite system. The peak of the storm
interfered directly with GPS frequency
bands, causing position errors, data
gaps, and tracking failures across
global airspace with hundreds of
spacecraft affected in Europe alone. The
ionospheric disturbances were so severe
that sudden jumps and deviations
appeared in aircraft flight tracks. Open
access data from the US Space Force
revealed more than 5,000 satellites had
to alter their position to avoid
deorbiting or crashing during the solar
storm. This is especially dangerous as a
single crash can lead to thousands of
pieces of space debris that can persist
for decades. These in turn increase the
risk of further crashes, creating a
vicious cycle. But the most dramatic
finding of all was what happened after
the storm.
Normally it takes 1 to two days to
replenish the plasmosphere after a
storm. But this one hit our plasmosphere
so hard it took more than 4 days to
bounce back. So what happened there?
About an hour after the solar wind
struck, intense heating near the poles
drove a surge of charged particles
towards the polar caps. This intense
heating churned the upper atmosphere
like a massive convective engine,
dredging up heavier molecular gases like
nitrogen and molecular oxygen from lower
altitudes into regions where they don't
normally exist in large quantities.
Under normal conditions, the upper
ionosphere is dominated by atomic oxygen
ions. But when nitrogen and molecular
oxygen flood into the upper atmosphere,
they react with the atomic oxygen ions,
reducing the concentration of those ions
in the ionosphere. This is known as a
negative ionospheric storm. And it's a
problem. Oxygen ions play a necessary
part in repopulating the plasmosphere
after a geomagnetic storm like this.
When a positive oxygen ion collides with
a neutral hydrogen atom in the
ionosphere, it takes the hydrogen's
electron since it has higher affinity
for electrons. This ionizes the
hydrogen, which then rises along the
magnetic field lines into the
plasmosphere. But with fewer oxygen ions
around it, the production line of
hydrogen ions was cut off at the source,
slowing the upward flux of plasma into
the plasmosphere to a trickle. This was
the first time the link between negative
ionospheric storms and delayed
plasmosphere recovery had been directly
and conclusively established. But the
sun wasn't done battering our
magneettosphere just yet. A few days
after the May 10th storm, a huge X-class
solar flare erupted, the strongest
category of solar flare. Despite its
effects on our Earthbased technology, it
was only ranked an 8.7 on the solar
flare classification chart. The
strongest flare on record, which
occurred in 2003, was estimated at 45,
about five times stronger. Yet, the
strongest geomagnetic storm ever was the
Carrington event in 1859, for which we
don't have a measured solar flare
ranking. However, the storm hit Earth so
violently that telegraph wires burst
into flames. Today, studies estimate
that if an equivalent event were to hit
the United States alone, it would cause
$600 billion to $2.6 $6 trillion in
damages.
20 to 40 million Americans would lose
power, though it's hard to say how long
for. Estimates range anywhere from 16
days to 2 years. It really depends how
quickly we can fix our transformers and
power grid infrastructure. And if
something like this were headed our way,
the scariest part is how little warning
we'd have. The key factor which
determines how devastating a CME would
be to us on Earth is the orientation of
its magnetic field. If it points
southward, that gives it the highest
probability of connecting with and
disrupting our own magnetic field.
The issue is we can't measure that
magnetic orientation until the solar
plasma reaches the L1 Lrange point, a
gravitationally stable location 1.5
million km from Earth in the direction
of the sun, where spacecraft can remain
in a hovering position relative to both
bodies. And by then, we'd only have 15
to 60 minutes to respond. And while
thanks to our thick atmosphere, us
Earth-based humans would be relatively
protected from the lethal radiation,
those who would suffer most are
astronauts. If a significant solar event
occurs when a crew is in space, it could
raise radiation levels inside their
spacecraft. Too much exposure over a
lifetime can increase the risk of cancer
or other health disorders that could
negatively impact cognition and
performance. For example, this was a key
consideration in NASA's recent Aretimus
2 mission with each astronaut being
given a personal radiation tracker.
Inside the Orion capsule, the hybrid
electronic radiation assessor system
contains six radiation sensors, which
measured dose rates in different parts
of the cabin. If radiation levels
increased, Orion's onboard systems
displayed warnings accompanied by an
audible alarm. So, what are we building
to better prepare for extreme solar
events that may happen in the future? On
the 23rd of January 2026, Noah's SWF L1
satellite arrived at the L1 point. The
spacecraft will use topofthe-line
instruments to make realtime
measurements of the solar wind, thermal
plasma, and the magnetic field.
Alongside this, it also carries a
compact chronograph instrument designed
to detect coronal mass ejections. It's
the first satellite Noah has fully
dedicated to continuous operational
space weather monitoring. In addition to
the SWF L1, NASA launched the
interstellar mapping and acceleration
probe or IMAP which is also stationed at
the L1 point. Its mission is to deepen
our understanding of how space storms
develop and dissipate, enabling improved
preparedness for adverse weather in the
future by providing real-time
observations of the solar wind. Vigil
mission will go further still. Set to
launch in 2031, it will be positioned at
the L5 Lrange point off to the side of
the Earth's sun line. From this vantage
point, it will be able to watch active
sun regions rotating towards Earth
before they face us, potentially
extending warning times from minutes to
days. On the ground, strides are being
made to reduce the risks of blackouts
and communication failures in the face
of future solar flares. For example,
implementing smart grid technologies and
high voltage search protectors in power
grids. building strategic transformer
reserves to quickly replace damaged
infrastructure and investing in new
materials like Faraday cages around
critical electronic components to
deflect electromagnetic pulses induced
by large storms. Slowly but surely, we
are preparing.
Solar cycle 25 exposed how much we still
don't know about our sun, but it also
brought us several breakthroughs. the
first photons of the sun's poles, a
revisited theory of its dynamo, the
discovery of switchbacks and how they
heat the corona, and so much more. Cycle
26 is set to start anytime between 2029
and 2032.
What it will bring, only time will tell.
But what's certain is we'll have even
more missions in space, even better
instrumentation ready and waiting to see
what we can learn this time around.
enjoy what we do, come join the Astramm
community today.