Last May amateur astronomers alerted the world to the fact that the gas giant planet Jupiter had lost a belt.
Normally the stormy world is encircled by two dark, rusty bands of clouds created by fast-moving jet streams. The features are easy to spot with a backyard telescope (and even easier with pro ‘scopes, such as Hubble or Cassini).
Jupiter in visible light, as seen by the Cassini space probe.
—Picture courtesy NASA
But seemingly out of the blue, one of the bands—called the south equatorial belt (SEB)—up and vanished in the spring, leaving only a zone of whiteness in its place.
“This is the most obvious change on Jupiter that I can recall,” Alan MacRobert, senior editor of Sky & Telescope magazine, told National Geographic News at the time.
Now, astronomers had seen this kind of thing before: Jupiter had lost the SEB in the 1970s and the 1990s, and both times it reappeared within one to three years.
Sure enough, by November the SEB was showing signs of a comeback, and scientists who had been watching the region were starting to paint a more detailed picture of what drives Jupiter’s colorful cloud bands.