Jupiter is the largest planet in our solar system. A large gas giant eleven times the diameter of Earth. The swirling masses of gassy clouds on its visible surface, its atmosphere, are characteristic of our distant neighbor. The swirling and encircling masses are driven by the planet’s fast rotation, and with a 10-hour rotational cycle, Jupiter is an object of much observation when it isn’t hidden by the sun. Much to the surprise of many observers, though, when Jupiter came back into view in May 2010, it didn’t quite look the same as it did in June 2009, before it disappeared behind the sun for its regular orbital trip away from Earth (Neatorama has the comparison images). Jupiter had lost one of its characteristic red stripes!
The red, brown, white, and yellow stripes of Jupiter are actually dense cloud patterns that scientists have termed belts and zones. The darker areas are the belts. Like Earth, Jupiter has an equatorial zone across its middle. Above and below this central swath of cloud are the equatorial belts, which usually appear as the two darkest bands on the planet. The missing stripe, or belt, on May 2010 was the Southern Equatorial Belt. Something happened to Jupiter behind the Sun that thinned out or changed the composition of this belt. Some astronomers surmise that it may have been storm activity, as the Great Red Spot is known to change color and fade as well, possibly due to alterations in sulfur and phosphorus content. The equatorial belt is thought to contain ammonia ice, sulfur, and phosphorus.
This phenomenon is not new. The Southern Equatorial Belt reappeared previously after a disappearing act in the early 1990s, and previous to that in 1973.The phenomenon of Jupiter’s missing stripes is thought to occur every 10 to 15 years. Some observers are saying that this occurrence was well overdue. An observer in Australia who tracked an asteroid’s impact with the planet’s surface last year noted to the Planetary Society (from DailyMail) that the disappearance was not all that unexpected because they could tell the band was fading last year before the planet disappeared in orbit.
Jupiter will be closest to Earth on September 24, 2010, which will allow observers to take a closer look at Jupiter’s stripes and determine if the Southern Equatorial Belt is starting to make a come back.
For more information on the planet Jupiter, see NASA.
