NASA's Cassini spacecraft took this true color mosaic of Jupiter, the most detailed global color portrait of the planet ever produced. The smallest visible features are approximately 60 kilometers (37 miles) across. Although Cassini's camera can see more colors than humans can, Jupiter's colors in this new view appear very close to the way the human eye would see them. The mosaic is made up of 27 images taken in December 2000, during the spacecraft's closest approach to the gas giant. The Cassini-Huygens mission is slated to arrive at Saturn in the summer of 2004. Photo released November 13, 2003. (UPI Photo/NASA) | License Photo
PASADENA, Calif., Nov. 26 (UPI) -- NASA images show one of Jupiter's stripes that "disappeared" last spring is returning, revealing clues about the planet's winds and clouds, U.S. scientists say.
Amateur astronomers noticed earlier this year that a long-existing standing dark-brown stripe on the planet known as the South Equatorial Belt had turned white, NASA said.
Telescopes in Hawaii including NASA's Infrared Telescope Facility and instruments at the W.M. Keck Observatory and the Gemini Observatory suggest the vanished dark stripe is making a comeback.
"The reason Jupiter seemed to 'lose' this band -- camouflaging itself among the surrounding white bands -- is that the usual downwelling winds that are dry and keep the region clear of clouds died down," said Glenn Orton, a research scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
In early November, amateur astronomer Christopher Go of Cebu City, Philippines, saw an unusually bright spot in the white area that was once the dark stripe.
"One of the things we were looking for in the infrared was evidence that the darker material emerging to the west of the bright spot was actually the start of clearing in the cloud deck, and that is precisely what we saw," Orton said.
The white cloud deck is made up of white ammonia ice clouds that float at a higher altitude, sometimes obscuring the "disappearing" brown stripe material, which floats at a lower altitude.
Every few decades or so, the South Equatorial Belt turns completely white for perhaps one to three years, NASA said.