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Jupiter's storms cover the planet, but the ones at the planet’s poles have mystified astronomers for years: why haven’t they merged together yet?

Hosted by: Hank Green

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[♪ INTRO].

The Great Red Spot is one of  Jupiter’s most striking features. Scientists first observed the storm back in 1664 and have regularly tracked it since the mid-1800s.

At its largest measured size, it  could fit three Earths inside of it. But Jupiter is also home to an arguably more intriguing population of  storms encircling each of its poles. We first learned about them in the mid-2010s, but to explain their existence, scientists  had to go back to math from the 1800s, which described a completely unrelated  phenomenon: floating magnets.

Cyclones on Jupiter are basically the  suped-up siblings of the ones on Earth. They follow similar trajectories, forming  near the equator and diverging toward a pole. It’s just that, on Earth, the storms  never actually make it to the poles:.

They run aground and lose energy. And the colder ocean waters also  provide less fuel as they go. Meanwhile, gas giants like Jupiter  have no surface to sap their energy, and their poles aren’t that  much colder than their equators.

So these storms make it all the way up  to the proverbial ends of the planet. In 2016, the Juno spacecraft observed a  set of six cyclones at the south pole, and nine in the north, ranging from four  to seven thousand kilometers across. There’s one storm about in the center, and the rest orbit around it at  roughly equal distances to one another.

And the systems have basically  been stable since then. But in theory, the storms should have  merged into one large storm at each pole, something reminiscent of the  hexagonal cyclone on Saturn. Why they hadn’t was a huge mystery.

So one team hunted for an explanation. And for some unclear reason, they traveled back  to the 1870s, and an experiment with magnets. Way back in 1878, American  physicist and professor Alfred Mayer published what was basically  a classroom demonstration.

It was about how molecules will naturally  arrange themselves into certain shapes. In the demonstration, he magnetized  needles and stuck each one in a cork floating on some water, with all the  magnets’ south poles pointing up. Then, he hung another magnet above the  setup with its north pole pointing down.

That way, the needles would be  attracted toward a central point, but they couldn’t get too close because their  matching south poles would repel one another. This forced the magnets into  different geometric arrangements depending on the number of needles. Really, it was just a big lesson in “like  repels like” and “opposites attract”; the stuff about magnets you learned in  elementary school, just applied to molecules.

And if you’re looking for the connection,  it had nothing to do with Jupiter. That part comes next. Not long after Mayer published his demo,  the British physicist William Thomson, eventually dubbed Lord Kelvin,  published some of the math behind it.

He showed how the needles will force  themselves into a certain state of equilibrium, balancing mutual repulsion  against their common attraction. And the number of needles changed  what those points of equilibrium were. Thompson published his  findings not long afterward.

And he also noted that Mayer’s  demo was a great analogy for column-shaped vortices orbiting  a mutual center of gravity. Now that might sound completely  unrelated to molecules to you, but at the time, Thompson hypothesized  that atoms weren’t particles, but vortices within a frictionless  fluid called ether that permeated space. This is not true, but his math was legit.

His proof showed that point-like vortices  could be spaced out symmetrically along the circumference of a circle,  remaining stable for up to six vortices. But once you tried to add a  seventh, it became unstable. And future work would show that adding a  sufficiently strong vortex in the middle could stabilize the system for as many  vortices as you cared to fit around it.

And this is of course where  Jupiter finally comes back in. This 2020 team realized that huh, maybe the storms on Jupiter could be  described with this old magnet math. They just had to convert magnetic attraction  and repulsion into something else.

And they did! The attraction became a cyclone’s  tendency to migrate toward the poles, which basically happens because of a  net wind that forms inside the storms, pushing them either north or south. As for the magnetic repulsion, that became  a special type of “shielding” on Jupiter, a ring of wind surrounding each storm  that rotates in the opposite direction.

And shockingly, this worked! The  math applied to Jupiter, too! Using computer modeling, the team  used these equations to figure out how strong that shielding effect needed to be to keep the storms in the stable  positions Juno was observing.

The number itself isn’t very  important, because it depends on the specific parameters of Jupiter’s  atmosphere and the storms themselves. Instead, the real point is that  the math is once again, legit! Equations from a century and a  half ago can finally describe the layout of Jupiter’s polar storms and  why they haven’t merged together yet.

That said, there are, of course,  still plenty of mysteries remaining. Like, we don’t know how or  where the cyclones first formed. We don’t know why the number  of storms has been so stable.

And we don’t know how this shielding  managed to form around Jupiter’s vortices, but not over on Saturn. So there’s almost just as many  questions as there were before. But eventually, knowing how the  superstorms on other planets work will help scientists better understand  the quirks of weather here on Earth.

And really, this serves as  a reminder that sometimes, you don’t need fancy new math or  computers to solve new problems. Sometimes, it’s just a matter of looking  for the right clues in the history books. Thanks for watching this episode of SciShow Space!

If that aspect of Jupiter’s  weirdness wasn’t enough for you, you might want to check out another  one of our Jupiter episodes, about how this giant planet is a  total jerk, but also our friend. [♪ OUTRO].