NASA's Jupiter Mission Juno Reveals Giant Polar Storms (bbc.com)

NASA's Juno mission to the gas giant Jupiter has reached its halfway mark and has revealed new views of cyclones at the poles. The BBC reports: As it orbits the planet every 53 days - Juno performs a science-gathering dive, speeding from pole to pole. Its sensors take measurements of the composition of the planet, in an effort to decipher how the largest world in our Solar System formed. Mapping the magnetic and gravity fields should also expose Jupiter's structure.

But images from JunoCam -- a camera that was intended to capture images that could be shared with the public -- has already given us some surprising insights. "When we made our first pass over the poles, we knew we were seeing a territory on Jupiter we had never seen before," said Dr Candice Hansen, from the Planetary Science Institute in Arizona. "What we did not expect was that we would see these orderly polygons of cyclones; huge storms - twice the size of Texas."

Comments

Why is this surprising?

[Anonymous Coward]

Why is this surprising? Saturn has a hexagonal pattern near its north pole. This arises from strong horizontal wind shears and the resulting barotropic instability. The result is that the flow breaks down into periodic vortices. This can be demonstrated in lab experiments and we observe it on Earth at other scales of motion. The eyewall of a hurricane frequently isn't circular, but tends to break down into a pentagon shape with five persistent mesovortices. The same process is responsible, just at a different scale of motion. The real question for me is what's different about Saturn's south pole that prevents this same process from occurring there.

Re:This really isn't that profound

[jd]

And that's part of the point. The storms at the poles are incredibly stable. They're the same storms as raged a year ago. Simulations of atmospheres like Jupiter's, either in the lab or on a computer, do show lots of short-lived storms, but usually those drift together to form a giant red spot.

There has been a question as to whether they've shown any other stable storms and the general consensus, insofar as I can ascertain, is no. I know of no simulation showing hexagonal storms, either. However, there will be plenty of simulations I don't know of, one of those might. That it caught everyone on the hop, it wasn't a prediction made in advance, suggests that it was not in any simulation.

Which means that there are complex processes on Saturn and Jupiter that we're not sure of.