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[♪ INTRO]
When you think about highlights of the night sky,
you’re probably not thinking about the Sun.
But depending on where you are in the world,
the Sun can create some of the most dramatic displays out there.
Near the poles, charged particles from the Sun create incredible light shows called auroras,
also known as the Northern and Southern lights.
These light shows get huge audiences, because they’re beautiful,
and also, they’re really useful for studying our planet and our solar system.
But even with locals, tourists, and scientists watching, back in 2015,
a group of citizen scientists in Finland saw a new kind of aurora
that had never been documented before.
And according to a paper published last week in the journal AGU Advances,
their discovery may be more than just a new spectacle in the night sky.
Scientists hypothesized that the unusual aurora
came from a feature in Earth’s atmosphere that we don’t actually know very much about,
but the aurora may give us a new chance to study it.
All auroras happen when Earth’s magnetic field funnels charged particles from the Sun,
or the solar wind, toward the poles,
where it hits nitrogen and oxygen in the upper atmosphere.
When they collide, the particles in the atmosphere get a boost of energy,
and when they relax back to their natural state, they let off that extra energy as light,
creating colorful bands or lines that stretch across the night sky.
And there are lots of kinds of auroras that have different shapes and colors,
depending on things like where they strike the atmosphere and how fast the particles collide.
So guidebooks help hobbyists tell apart the different types,
but the one discovered in 2015 wasn’t in the guidebooks.
It was green, like a lot of auroras,
but it looked almost like a bunch of fingers stretching parallel to the ground.
The group called the new auroras “the dunes”
because of the way they appear to ripple like sand dunes.
And their shape was a little surprising.
Since Earth’s magnetic field is mostly vertical near the poles,
most auroras look like they stretch upward, toward space.
But the dunes were horizontal.
So the group got in touch with a local physicist
who wrote one of the aurora guidebooks to learn more.
Except, she had never seen anything like it.
So in 2018, she organized a group of people
to photograph and document these auroras all over Finland and Sweden.
Once they’d collected the photos,
the hobbyists teamed up with the author of the guidebook and her colleagues
at the University of Helsinki to understand how the dunes were forming.
They worked out the altitude by comparing photos from multiple locations;
a lot like how your brain creates depth perception by comparing the view from each eye.
They showed that the dunes were about a hundred kilometers above the ground,
which is pretty typical for an aurora.
But they also noticed that you couldn’t see the dunes
if you were directly beneath them, which suggested that,
unlike other auroras, they were pretty thin vertically.
Also, since the light wasn't continuous,
it likely pointed to some unevenness in the atmosphere that was emitting the light.
So scientists inferred that the auroras
were coming from a bunch of thin ripples in the atmosphere.
Ripples like this, known as atmospheric waves, can form for different reasons,
but the team figured out that, in this case,
they might be a sign of a phenomenon called a “mesospheric bore.”
This feature seems to form when large-scale winds
that blow across our planet change direction or speed.
Bores are still a little mysterious, though.
Scientists are working on figuring out the details of how, why, and where they happen.
But the dunes could actually help with that.
In the past, scientists had seen bores near the equator,
but not so much at higher latitudes.
So the dunes give scientists a brand-new way of studying them up there.
They act as a sort of flashlight that highlights
what’s happening at higher layers of the atmosphere.
And these bores, along with other atmospheric phenomena,
can teach us how our own atmosphere responds to seasonal and solar changes.
While auroras can give us an indirect look at what’s happening on the Sun,
a new telescope has given us our most direct look at the Sun ever.
Last week, the National Science Foundation’s Daniel K.
Inouye Solar Telescope in Hawai’i released its first photos of the Sun’s surface.
And they look amazing.
They’ve let us see the Sun’s surface in the highest resolution yet.
By getting this close-up look, scientists are hoping to better understand
how the activity on the Sun is connected to its impacts back home.
Because radiation from the Sun can do a lot more than give us pretty light shows;
it can also knock out satellites or mess with our communication systems.
So it’s important to understand it,
but it’s also hard because the solar wind that causes auroras isn’t constant.
Sometimes it’s like a gentle breeze, and other times it can be pretty violent.
That variation is tied to the hot gas and plasma
that are constantly bubbling up from the Sun’s interior.
When they reach the surface, they cool off and they sink back down again.
Some of these individual bubbles are truly enormous:
about as wide as fifteen Earths.
But a lot of these bubbles are way smaller, like, just a few kilometers wide.
They were way too small for other telescopes to notice, so we’d never seen them.
But this new telescope uses a gigantic,
four-meter mirror to resolve bubbles that are just thirty kilometers across.
That’s about five times smaller than we’ve ever seen before.
And these bubbles are important!
They’re key to understanding what’s happening on the Sun,
which can give us clues about when and why it acts up.
The telescope will also let us investigate the Sun’s corona,
the mysterious outer region that seems like it should be cooler than the solar surface,
but somehow, is millions of degrees hotter.
And given that it’s capable of recording so much detail,
the project’s scientists say that five years of data from this telescope
will contain more information than we’ve ever gotten
from all of our previous solar telescopes combined.
So stay tuned. Because the Daniel K. Inouye Solar Telescope is just heating up.
Thanks for watching this episode of SciShow Space, which is produced by Complexly.
If you want to keep imagining the world complexly with us,
check out Animal Wonders hosted by Jessi Knudsen Castañeda.
Animal Wonders is an animal rescue and education facility that cares for
nearly 100 exotic animals and wildlife that can’t survive in its natural habitat.
Every week on the Animal Wonders YouTube channel,
Jessi features different animals and shares what it’s like
to keep them happy and healthy.
Recently, Jessi and the Animal Wonders team took in Tigli the arctic fox.
If you’d like to learn all about Tigli’s story
and find out how he’s getting along with the other foxes at Animal Wonders,
you can follow the link in the description to a video all about that.
[♪ OUTRO]