New Red Spot Options

[Guest_Sunspot_*]

http://science.nasa.gov/headlines/y2006/02....htm?list771283

[Bjorn Jonsson]

The constantly changing appearance of Jupiter's atmosphere is a fascinating subject. Many of these changes are quite obvious in amateur astronomical telescopes once you are familiar with Jupiter.

The origin of this 'new' red spot can be traced back to 1939 when the three white ovals seen in the Voyager images started forming. They were formed as a result of changes in three separate locations in the South Temperate Zone. Originally they were very long but then steadily contracted, rapidly at first. They were extremely similar to the GRS. These three ovals were known as BC, DE and FA. As previously noted, originally they were very long. At that time they were separated by dark segments known as AB, CD and EF.

In 1998 ovals DE and BC merged into a single oval labeled BE. In March 2000 ovals BE and FA merged into a single white oval (oval BA) visible in the Cassini images. In 2005 this single surviving oval started changing color and in 2006 it had turned red. Interestingly, HST observations revealed that wind speeds in the spot increased after it turned red.

There is a huge amount of information on Jupiter's long term behavior in John Rogers' excellent book The Giant Planet Jupiter (to anyone interested in this subject: If you don't have it, get it!). Patrick Irwin's Giant Planets of Our Solar System discusses this in less detail but from a more technical perspective. There's also some information here and in particular here.

Perhaps even more interestingly, the GRS may disappear in a few decades. It has been steadily contracting and if the same trend continues, by 2040 or so it will be circular. That's believed to be an unstable configuration so something interesting is going to happen - the big question is, exactly what?

Finally I'll end this by venting my frustration: I cannot observe Jupiter until 2010 due to my northerly latitude .