DPS: New stuff from New Horizons at Jupiter

I'm already on my way home from the Division of Planetary Sciences meeting in Orlando, which will continue there for the rest of this week. Overall, it was not quite as exciting as some of the previous DPS meetings I've been to. Most of the presentations were refinements or updates of things I've seen before, rather than new results; they were interesting, but not Earth-shattering.

A case in point was the New Horizons results from Jupiter; there was a special session yesterday (Tuesday) and the first scientific publications from the encounter are coming out in Friday's issue of the journal Science. But most of the stuff they presented -- spectacular though it is -- I had already seen at the icy satellites conference in Boulder in August (you can read about that here). There were a couple of new items, though

Amy Simon-Miller presented on "Jovian Winds and Waves from New Horizons." She showed various interesting features in the moving bands and belts of Jupiter's clouds, but some of the coolest were what she called "mesoscale gravity waves" near Jupiter's equator. They are like ocean waves in that the waves propagate through the medium of Jupiter's atmosphere with a speed that is different from the speed of the moving atmosphere itself. Their wavelength is small by Jupiter standards, only 300 kilometers from peak to peak, striping Jupiter's equator with a faint fishbone pattern. And they move fast -- by tracking wave features, Amy found that they move 100 meters per second faster than the atmosphere itself is moving. She found the waves in images taken by New Horizons' color imagers, MVIC and LEISA, in observations that were designed not for science but for instrument calibration; the science was a bonus.

The most amusing part of Showalter's presentation was when he compared images of the rings from Voyager and Galileo to images of the rings from New Horizons. If you look at every Voyager and Galileo image, he said, you see "quadrant asymmetries," meaning that one side of the rings appeared brighter than the other, which was deeply puzzling to ring scientists. But in every single New Horizons image of the rings, the rings are symmetric in brightness. "We can breathe a sigh of relief that a problem that we completely didn't understand is now gone, so the problem is solved," he joked. Of course, the fact that the weird phenomenon has apparently disappeared over a very short time frame really just adds to the puzzle.

John Spencer presented the Io volcanism results, which I have covered extensively before; I'll only add this nifty map of places where there have been surface changes on Io since the volcanic moon was observed by Voyager and Galileo, and a diagram that he presented on how differences in the solar illumination angle can make lava flows on Io disappear and reappear.