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Life on Earth just wouldn’t be the same without our Sun.
But this star also comes with some downsides; it can unleash solar winds that
travel all the way to Earth, affecting satellites and even the power grid.
So to better predict these phenomena,
scientists have sent a car-sized craft to the Sun: The Parker Solar Probe.
And in 2021, it finally touched the Sun!
So here’s what we have learned from the probe’s long journey.
The Parker Solar Probe is a spacecraft with a big mission:
to fly to the Sun and uncover the mysteries of solar winds.
These are not like the winds you experience here on Earth; they are
streams of charged particles that get ejected from the Sun’s atmosphere.
After they leave the Sun, these winds can reach over 500 kilometers per second.
They are so fast that they can damage solar panels when they collide with spacecraft.
And solar winds not only wreak havoc in space, but also on Earth.
When solar winds hit our planet, they can send a shock through our magnetic field,
in extreme cases affecting almost everything that relies on electricity,
from electronics to power grids.
To study these effects up close, scientists sent the
Parker Solar Probe to the Sun to uncover how solar winds move.
As it approached the Sun, the Parker Solar Probe sent data back to Earth
showing that the Sun isn’t /only/ blowing solar winds away; they can fluctuate.
Solar winds generally emanate away from the Sun, but not always.
The probe measured switchbacks, where a stream of solar wind
speeds up and then doubles back on itself.
It’s the equivalent of taking two steps forward and then one backward.
But the researchers needed a closer look to figure out
what was triggering the switchbacks.
So the craft went full steam ahead on its mission, getting closer to the Sun than
anything we’ve sent to space before.
And on April 28, 2021, the Parker Solar Probe finally touched the Sun.
Now, the Sun does not have a hard outer layer like the Earth or the Moon,
making it hard to define its boundaries.
But researchers have somewhat settled on the idea that entering the Sun’s
atmosphere is touching it, and that is where the solar probe was in 2021.
So when the probe touched the Sun, it withstood those hammering solar winds
and gathered the data we need to fill in missing details about solar wind particles.
And what it found was a solar traffic jam.
When fast solar winds in the Sun’s atmosphere
move in behind slower solar winds, they get stuck in gridlock.
Just like on the highway, you can be driving at 100 kilometers per hour on
an open road until you hit a patch where people are
driving at 80 kilometers per hour in front of you.
Now you have to slow down because the slow cars are blocking your path forward.
When you hit this point, the space between your car
and the car in front of you gets smaller.
Now replace the cars with gusts of wind.
This phenomenon is called compression because the winds are close together
in one spot compared to the rest of the time when they’re more spaced out.
And the Parker Solar Probe found that these compressed winds
usually happen near coronal holes, where solar winds are faster.
Coronal holes are pockets of Sun plasma that are cooler
and less dense than other parts of the Sun.
And because these holes are less dense,
they are an easy escape route for solar winds.
So solar winds that exit through coronal holes can travel faster
than winds coming from other areas of the Sun.
It’s like running through a field of tall grass.
You’d run slower through fields with denser plant growth than those
with only a few plants to make your way through.
And the probe recorded all of this playing out while it traveled through the winds.
It observed how the particles from the compressed winds weren’t changing intensity
or speed, so the particles seemed to be trapped in that area.
The Parker Solar Probe’s measurements indicate that
switchbacks also come from coronal holes.
Several research groups have suggested that switchbacks happen
because fast winds come up behind slow winds.
So the wind’s respective velocities can distort how they move through space,
forming compression and switchbacks.
And researchers are hoping to learn to use the data from the probe to predict
when these traffic jams and accelerations will happen, so that people here on Earth
can protect our satellites and avoid damage from solar weather.
So we are likely to speed up our understanding of the Sun in the next few years
as the Parker Solar Probe goes deeper and deeper into our favorite fireball.
Until then, you can bring a tiny version of this probe along with you
as you go into your own adventures, because it is April’s pin of the month!
This month’s pin features the tiny but mighty Parker Solar Probe
and it’s available all month at DFTBA.com/SciShow.
It’s only available in April, so make sure you order yours soon if you want it.
In May, we will have a whole new pin for you
that'll be part of this year's theme: exploring our solar system.
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