[♩INTRO]
Sometimes, astronomers can seem obsessed with finding water
on other planets and moons, so you’d think it was super rare in the solar system.
But it’s really not, and now we know of yet another place that might have water.
It’s just not one you might expect.
In this month’s edition of the Astronomical Journal,
scientists reported hints of a water cloud deep within Jupiter’s Great Red Spot.
It’s not a sign astrobiologists should start looking for life there or anything,
but it could help solve the mystery of how the largest planet in our solar system actually
formed.
Like the other gas giants, Jupiter is mostly made of hydrogen and helium.
But astronomers have spent over a century trying to pin down
what other compounds it’s made of, and how abundant they are.
Among other things, that could help us understand how and where the planet formed.
For example, knowing how much water, or how much oxygen, Jupiter has
could help answer the question of how far away from the Sun it had to have started.
So far, computer models have been able to help a bit with these questions.
They suggest Jupiter has three different cloud layers:
The uppermost has a lot of ammonia, and below that it’s ammonia and sulfur.
The bottom layer, though, is suspected to have water, both in solid and liquid form.
But physical evidence of that water has been a bit elusive over the decades.
And that’s where this new study helped.
This team analyzed data of the Great Red Spot, a centuries-old storm larger than Earth.
Specifically, they used infrared data from a few telescopes and the Cassini spacecraft,
which allowed them to penetrate Jupiter’s opaque upper layers
and get a look beneath the planet’s surface.
They weren’t directly looking for water, though.
Instead, they were mostly measuring the amount of a type of methane gas.
The abundance of this gas is roughly uniform in Jupiter’s atmosphere,
so if the group saw that abundance changing at all,
it was likely that something, like a cloud layer, was blocking their signal.
And that’s exactly what they found!
By studying the light traveling through Jupiter’s clouds,
the team could determine exactly how far down those different layers were.
Then, based on the pressures and temperatures at those depths,
they could figure out what kinds of compounds could exist there.
In the end, they did find three cloud layers, just as earlier models predicted.
The deepest was 160 kilometers down,
where the atmospheric pressure is around five times that of Earth’s at sea level,
and the temperature is just above the corresponding freezing point of water.
That pressure and temperature suggests the presence of water down in those clouds,
but right now, it definitely doesn’t prove it.
We’ll need more research to actually be sure.
Luckily for us, we currently have someone, or someTHING, on the case.
Right now, the Juno spacecraft is investigating water on, or in, Jupiter.
And it can look deeper than any of our other tech,
up to where the pressures are 100 times that of Earth’s atmosphere.
So the team is waiting for our local planetary probe to back up their work.
If it does, then we’ll be able to further investigate water on Jupiter
and maybe learn more about its origins, too.
Finding water on Jupiter would stick it in the same category
as a bunch of other objects in the solar system,
but don’t worry: Jupiter is still super special.
In fact, according to research published in Nature this Wednesday,
it might have a magnetic field completely unlike any other planet.
For the last couple of years, our little friend Juno has been doing more
than just looking for water: It’s been mapping Jupiter’s magnetic field.
Astronomers had already crafted a new, more accurate model
for the field outside Jupiter, based on eight of the spacecraft’s passes
around the planet, things like how strong it is and where.
But instead of looking at its surface, this team looked beneath
the planet’s cloud tops, up to a depth of 15% of Jupiter’s radius.
There, it’s suspected that the hydrogen inside Jupiter becomes a metallic fluid,
which allows it to conduct electricity and generate a magnetic field.
But that analysis showed something super weird.
The team found that Jupiter’s magnetic field
looks different across the northern and southern hemispheres.
In the north, it’s not a dipole, like you see in diagrams of the Earth’s magnetic field.
But in the south, it is — and it’s much weaker.
The group measured something called the magnetic flux,
or how strong a magnetic field is as it passes through a certain area.
And they found that most of the flux comes out of the planet in a small band in the north.
Then, some of it loops back around
and reenters the planet in a region near Jupiter’s equator, called the Great Blue Spot.
Based on this, the team proposes that
the mechanism that powers Jupiter’s magnetic field has to operate differently
than what we’re used to seeing elsewhere in the solar system.
It’s not like on Earth,
where a thick shell of some electrically conductive fluid rotates as a single body.
Instead, there could be different layers,
like different densities of metallic hydrogen at different depths.
Or the layers could be better or worse at conducting electrical charge.
Maybe some helium rain is up to something,
or maybe it has to do with dissolved parts
of the planet’s rocky, icy core, which is predicted by some studies.
This new paper brought up a bunch of cool new questions,
and we just don’t know what’s going on yet.
Like with the water mystery, we need Juno to collect more data.
For the moment, though, it definitely looks like Jupiter’s magnetic field
isn’t like anything we’ve seen before.
So even if the planet turns out to be full of water, Jupiter is still in a class all its own.
Thanks for watching this episode of SciShow Space News!
If you’d like to learn even more about the weirdness of Jupiter’s Great Red Spot,
like where it came from and how long it’ll exist, you can watch our episode all about it.
[♩OUTRO]