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Monday, 2 July 2012

[BAA-ebulletin 00682] Jupiter reappears with major outbreaks in northern hemisphere

BAA electronic bulletin

Jupiter reappears with major outbreaks in northern hemisphere

John Rogers (BAA), 2012 June 30

As Jupiter is now emerging in the morning sky, two very important disturbances are under way on the planet. They were nearly missed due to solar conjunction, and it is urgent to observe these rapidly changing phenomena now.

The disturbances are in the North Equatorial Belt (NEB) and North Temperate Belt (NTB).  Both belts had faded (lightened) during 2011, and were very quiet in early 2012.  The NEB was exceptionally narrow and its south edge devoid of major features, a state not seen since about a century ago.  The disturbances erupted just before Jupiter disappeared behind the Sun, and were only detected thanks to the perseverence of a few observers.

The NEB outbreak [ref.1] began on 2012 March 8 when a bright 'rift' appeared and started to generate very dark, slow-moving formations on the NEBs edge.  It seemed possible that this would be the start of a new NEB broadening event (last seen in 2009), and perhaps of a fully-fledged 'NEB Revival' such as used to happen a century ago.  The NTB outbreak [ref.2] was first detected on April 19 with a very bright and a very dark spot on the NTBs edge.  It seemed likely that this was the start of a new NTBs jet-stream outbreak (last seen in 2007).  Both events would be spectacular, and important for establishing the long-term patterns of activity in Jupiter's atmosphere, so it was frustrating that Jupiter then disappeared behind the Sun.  We eagerly awaited the new apparition to find out how the phenomena developed.

Manos Kardasis in Greece made the first image of the new apparition on June 4, which confirmed that both outbreaks had developed impressively. He has posted a map made from his near-infrared (IR) images on June 4-9 [ref.3].  Other observers have also made great efforts to get images, in daylight or at low altitude, and the patterns of the outbreaks are now emerging [ref.4].  There are striking dark spots in NTropZ and on NEBs, and reddish or ochre colour appears to cover much of the NEB, NTropZ, and NTB(S). These images provide strong evidence that a NTBs super-fast outbreak has indeed occurred, and that a NEB Revival is under way.

Our new report [ref.4] is a compilation and tentative interpretation of the images from June 13-14, posted.  More observers are now obtaining better images, so the interpretations may be revised, but the appearance of the outbreaks may change rapidly, so this preliminary report may still be useful as a guide to what is happening.

These reports have been posted as follows, both on the BAA Jupiter Section web site and, thanks to the ALPO-Japan, on their web site:

[1]  2011/12 Report no.5.  The NEBs outbreak in 2012 March. (2012 April)

[2]  2011/12 Report no.6.  Major outbreak on NTBs jetstream (2012 June)
         [Updated from an alert sent out on April 25:]

[3]  Alert:  Major outbreaks occurring on Jupiter. (2012 June 12)
        [e-mailed to Section members, & posted at:]

[4]  2012/13 report no.1: Jupiter reappears with major outbreaks on NEB and NTB (2012 June 27).


John H. Rogers, Ph.D.
Jupiter Section Director,
British Astronomical Association


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