British Astronomical Association
Supporting amateur astronomers since 1890

Secondary menu

Main menu

BAA Articles

New apparition of Jupiter, new Section web pages, and major change in a belt

New apparition of Jupiter, new Section web pages, and major change in a belt

The first good images of Jupiter since solar conjunction suggest that a ‘NEB expansion event’ is underway, i.e., broadening of the North Equatorial Belt (NEB) northwards into the N. Tropical Zone. Such an event had been predicted to occur in 2015 [  - go to no.5], and during the first half of the year, there were signs of increased emission of dark material northwards from the NEB, which could have been the early stages of the expansion event, but did not develop convincingly until during solar conjunction.

According to the latest maps produced by Marco Vedovato (such as the one attached), there is a distinct broadened sector for ~95º following White Spot Z (WSZ), from L2 ~ 315-50. The recent maps suggest that it is beginning to spread around White Spot Z. Another notable newfeature is the ‘Northern Red Spot’ (NRS); such dark reddish-brown anticyclonic spots are often produced before or during NEB expansion events.  The full bulletin on this event is at:  

If this is really the start of a NEB expansion event, it is likely to spread around the planet over the next few months, and observations will be of great interest. Will it spread steadily westwards, or will broadening develop irregularly at other longitudes, possibly with one or more secondary sources of expansion? Will there be interactions with mid-NEB rifts, and effects on the NEBs dark formations? Methane-band images, especially when the expansion nears completion, could show whether the wave phenomenon of 2000 is repeated. About a year from now, when the belt is fully expanded, a new array of barges and AWOs should start to emerge.

This report is the first item on a new web page for the BAA Jupiter Section, on which reports for the 2015/16 apparition will be posted (with north up in illustrations, to liaise better with NASA's upcoming Juno mission). This is accessible through the BAA home page, or directly at: .   The older Section web site remains operational with material up to 2015, including much background material on Jupiter.


Like This Article