This image of Jupiter's white ovals BC and DE was taken by the Galileo spacecraft
Click on image for full size

White Oval Trains

Like sailboats in the ocean, the white ovals seem to drift eastward faster than the underlying current which carries other cloud formations in the South Temperate Zone (STZ). Since their birth , the ovals have changed both their appearance , and the speed at which they drift to the east.

Oval FA drifted the fastest, and by 1987 was on the other side of Jupiter from where they were born. Oval BC is next eastward-most oval. Oval BC is also the biggest of the classic ovals. Oval BC and oval DE drift at different speeds, thus one might expect that they might run into each other. It seems however that for 60 years, BC and DE have had close encounters, coming to within 18 degrees of each other, but repel each other when they get too close. One will speed up, or the other will slow down so that they always stayed apart.

Other white ovals nearby are situated slightly to the south of these three. Since BC is the largest of the ovals it seems to hog the space within the STZ, and not allow the other white ovals, WO1, WO2, and DE to get by. The picture shows BC at the eastward-most end, with a train of white ovals trailing along behind.

In 1998, BC and DE had their final close encounter and merged to form a new oval called BE.

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