It’s been almost a year since Juno first got to Jupiter, and ever since, the probe’s
been sending back incredible photos and data for scientists to analyze.
Now, the mission team has finally announced Juno’s first findings in a couple of papers
published last week in the journal Science.
And just these first results are totally changing the way we think about Jupiter.
We’re learning more about things like the planet’s atmosphere, internal structure,
and magnetic fields.
And a lot of it is totally unexpected!
Part of the reason Juno’s results are so surprising is that the probe is studying Jupiter
in ways we’ve never been able to before.
It’s armored against the powerful radiation around the planet, allowing it to skim just
5000 kilometers above the cloud tops.
And unlike most spacecraft, which usually travel around a planet’s equator, Juno’s
orbit takes it over Jupiter’s poles.
From our first good look at these regions, we’ve learned that Jupiter’s famous red
and white stripes disappear completely.
Instead, the poles have a mess of enormous cyclones.
A lot of them are as big as the largest storms we’ve ever seen on Earth.
Jupiter’s poles are also home to the solar system’s largest auroras, the beautiful
light displays that happen when electrically charged particles strike the upper atmosphere.
And thanks to Juno, we’re learning that some of our assumptions about how they work
were totally wrong.
On Earth, these particles come from the solar wind rushing out of the sun.
Most of them are deflected by Earth’s magnetic field, but some leak through and strike the
poles to create the northern and southern lights.
Until now, we assumed that the process on Jupiter was pretty similar.
But Juno found that the particles that create auroras on Jupiter move differently — they
seem to be pulled up from the atmosphere.
Even Jupiter’s magnetic field turns out to be full of surprises.
Juno found that it’s ten times stronger than the one su rrounding us here on Earth.
We knew Jupiter’s magnetic field would be strong,
but we didn’t know it would be that strong.
And that’s not the only weird thing we’ve just learned about the magnetic field.
Generally, the farther you are from a planet, the weaker its field becomes, but Juno found
major exceptions to this rule.
Jupiter’s magnetic field is kind of … bumpy.
It’s stronger than you’d expect in some places, and weaker in others.
Astronomers think the variation comes from the planet’s dynamo, which is an awesome
name for the conductive fluids sloshing around in a planet’s core.
A dynamo seems to be what creates planetary-scale magnetic fields.
The fluid in Earth’s dynamo is molten iron, but the interiors of the gas giants are a
lot different from rocky worlds like ours.
Juno’s observations suggest that Jupiter’s dynamo consists of an enormous region of liquid,
electrically conductive hydrogen.
You’d normally think of hydrogen as a gas, but the ridiculously strong pressure inside
Jupiter compresses it into a liquid.
It takes more than just measuring the magnetic field to understand the planet’s interior, though.
That’s why Juno has been mapping out Jupiter’s gravitational field.
Just like a magnetic field, gravity generally gets weaker the farther away you are from
a planet.
But if a planet’s mass isn’t distributed evenly, that’ll affect the strength of its
gravitational field in different places.
So, small variations in the gravitational field can point to inconsistencies within the planet.
Astronomers measure a planet’s gravity by tracking the speed of the spacecraft itself.
If there’s a stronger gravitational field somewhere, the extra pull will make Juno go faster.
By mapping these speeds, researchers can figure out how matter is distributed inside Jupiter,
going all the way down to the center.
And that’s where they found another surprise.
Astronomers used to think that if Jupiter had a solid core at all,
it was probably pretty small.
Instead, Juno’s measurements imply that the core is much larger and more spread out
than we thought.
It might even be partially dissolved in the liquid hydrogen around it.
Gravity isn’t the only way Juno’s designed to look deep into Jupiter.
Its microwave detectors can measure the radiation emitted by molecules hundreds of kilometers
below the visible clouds.
And Juno discovered something both remarkably familiar and weirdly different down there:
big looping structures called Hadley cells.
On Earth, air circulating in Hadley cells is responsible for tropical rainforests and
the east-west trade winds that help ships move across the oceans.
On Jupiter, these cells seem to be made up of huge, ammonia-filled currents that move
separately from the clouds that make up the planet’s stripes.
They’re an early sign that the deep atmosphere is way more complex than we thought.
That’s just one of the things that Juno is slated to continue studying into next year.
Eventually, radiation will start to damage the probe’s instruments and contaminate
the collected data, and the mission will have to end.
But by that point, we’ll have tons of new data about Jupiter — including detailed
maps of what’s going on inside the planet.
And that’s exactly what scientists need to start solving all these new mysteries.
Thanks for watching this episode of SciShow Space News, and thanks especially to our patrons
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