Jupiter's 'missing' brown stripe makes a comeback as weather on giant planet changes



One of Jupiter's stripes that 'disappeared' last spring is now showing signs of a comeback, Nasa has confirmed.

Earlier this year, amateur astronomers noticed that a longstanding dark-brown stripe, known as the South Equatorial Belt, just south of Jupiter's equator, had turned white.

Now scientists believe it has returned.

These new observations will help scientists better understand the interaction between Jupiter's winds and the clouds that circle the planet.



Jupiter's South Equatorial Band has been seen to change colours before, although the change has never been recorded in such detail. Far infrared images, depicted in red, show a powerful storm system is active above the returning dark belt

‘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 Nasa research scientist.

‘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.’

This white cloud deck is made up of white ammonia ice. When the white clouds float at a higher altitude, they obscure the missing brown 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, an event that has puzzled scientists for decades.

This extreme change in appearance has only been seen with the South Equatorial Belt, making it unique to Jupiter and the entire solar system.

The white band was not the only change on the big, gaseous planet. At the same time, Jupiter's Great Red Spot became a darker red colour.

