Jupiter’s Circulating Current

Even casual observers recognize the Great Red Spot on Jupiter, and more recently its smaller sibling oval BA, affectionately dubbed "Red Jr." But besides taking an occasional glance at these interesting storms, you can also contribute to the study of Jupiter's many changing belts, zones, and currents.

Using amateur photographs, John Rogers has documented the circulation of a number of small spots throughout the month of July. Click above for more images. South is up.
Various astrophotographers worldwide
John Rogers, Jupiter Section Director of the British Astronomical Association, has been tracking a very interesting current that circulates between the South Equatorial Belt (SEB) and the South Temperate Belt (STB). It pulls small dark spots from the westward-flowing SEB and transfers them to the eastward-following STB, causing the spots to reverse directions over the course of a few days.

This phenomenon was first recorded by visual observers in 1920 following the SEB revival of that year, it was noticed again in 1932–34, and it may have recurred a few times since then. But this is the first time that the process has been documented by photographs. And thanks to the worldwide network of amateur planetary imagers, there's a nearly unbroken record showing how the event progresses hour by hour.

Continuing observations are welcome. Anyone with a webcam and a 6-inch telescope can capture these events. And please send us your images.