As I've written about several times, a few months ago Jupiter lost one of its belts. Normally there are two dark, wide bands of clouds framing its equator, but the southern one disappeared recently. It's happened before, and the cause isn't well-understood (I favor the idea that it sinks a bit, and a layer of opaque clouds flow over it, hiding it from view). It always re-appears sometime later.
And that seems to be happening now. As my pal Emily Lakdawalla reports on The Planetary Society blog, there are odd atmospheric phenomena occurring where the belt should be, and they appear to be on the rise. In the picture here (from Emily's blog; go there to get an enjovianted version) I've arrowed the outbreaks, which appear as a series of comma-shaped dark clouds. If true, this could be the harbinger of Jupiter's belt resurfacing.
I hope so, actually. If we can point some big ol' 'scopes at the planet while this happens, maybe we can figure out what the heck can cause a raging storm wider than the Earth to suddenly drop out of sight for months or years at a time!
This may actually do something otherwise difficult, too: it's inspiring me to haul my own telescope out of the garage to give Big Jupe a look-see. If the belt's coming back, I want to make sure I can see it while it's still gone. Plus, with friends and family visiting for Thanksgiving this week, it's a great time to show them the sky (though cold here in Boulder). It's very odd to see Jupiter with one off-balance belt; I've observed the planet hundreds of times since I was a kid and I always expect to see the two dark bands surrounding the lighter colored equator. If and when the belt comes back, who knows when it'll go away again?
Image credit: Teruaki Kumamori, Sakai City, Osaka, Japan