Earlier this year, astronomers observing the planet Jupiter noticed that it’s usually prominent Southern Equatorial Belt (SEB) – a band of darker cloud in Jupiter’s otherwise pale surface – had disappeared. This was not the first time it had happened: in 1973 when Pioneer 10 flew past Jupiter the belt was absent, and it vanished again in the early 1990s.
But there are now signs that the Southern Equatorial Belt is reviving. The BAA Jupiter Section Director John Rogers explains:
“A spectacular bright plume has appeared in Jupiter’s faded South Equatorial Belt, and is expected to become the source of spectacular disturbances leading to revival of the belt.
“This rapidly brightening plume is so energetic that we can confidently expect it to develop into the SEB Revival. The SEB Revival is usually spectacular, so we can expect impressive and rapidly changing disturbances over the next 3 months, until the end of the apparition. As the SEB is so thoroughly whitened, and the outbreak has appeared in an isolated location, we can hope to see the phenomena displayed in their most complete form.
“Normally, disturbances continue to arise at the same source, and spread out in three branches: northern and central branches, prograding, and a southern branch, rapidly retrograding. If they develop as usual, both the central and southern branches could impact on the Great Red Spot in January. Observers should monitor all aspects of the spreading disturbances, but also monitor other longitudes, as a secondary source might also appear. Observers have the chance to make this the best-observed SEB Revival ever.”
The initial observations of the bright plume were a truly international affair, as John Rogers explains:
“The bright plume was discovered by Christopher Go (Philippines) in an image which he took on Nov.9 at 12:30 UT. He announced it immediately by e-mail, and it was confirmed 11-12 hours later by Donald C. Parker (Florida, USA) and Gary Walker (Georgia, USA), when it was already brighter.
“Don Parker’s images included infrared, ultraviolet, and 0.89 micron (methane) bands, and the new spot was amazingly bright in all of them, showing it to be a convective plume of cloud reaching to very high altitude. Indeed it was already visible in a methane-band image taken in poor seeing by A. Yamazaki (Japan) on Nov.9 at 14:14 UT. On its third rotation, Nov.10 from 09:00 UT onwards, images by many Japanese observers and by C. Go and T. Akutsu (Philippines) confirm that it is the brightest spot on the planet in all wavebands. Its longitude is L2 = 290 (L3 = 149). (The Great Red Spot is at L2 = 159.)
“This plume has appeared inside a cyclonic circulation, called ‘barge B2′, which had been very dark a year ago, but turned white in 2010 May-June. Details of this are available on the BAA’s Jupiter Section website:
http://www.britastro.org/jupiter/2010report08.htm [Figure 11].
“Thus the former barge already comprised a white spot, but it was not methane-bright (up to Nov.7: Chris Go). It was still quiet on Nov.8 (Sadegh Ghomizadeh, Iran). So the much brighter plume was new on Nov.9. We had already suggested that the SEB Revival might begin with such a plume in one of the barges, as it did in 2007; the event is a striking confirmation of this hypothesis.”