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Great Red Spot III

August 20, 2014

Jupiter’s Great Red Spot appears to be on a diet. It’s slimmed down by thousands of miles, and the loss has accelerated in recent years. Planetary scientists say there’s no way to know what will happen next.

Back in the 19th century, the oval-shaped storm was roughly 25,000 miles wide — about three times the diameter of Earth. By the time the Voyager spacecraft flew past Jupiter in the 1970s, the spot had shrunk to twice the diameter of Earth. And this year, Hubble Space Telescope measured its length at not much more than one Earth diameter.

The Great Red Spot is flanked by strong jet streams. Interactions between the jet streams and the spot spin off eddies. They travel all the way around the planet, and then merge with the red spot, adding energy to the system. But Rita Beebe of New Mexico State, an expert on Jupiter’s atmosphere, says that fewer of these big eddies have merged with the red spot in recent years.

BEEBE: We really think the way it has lived all these years is the same life cycle as in the ocean: big fishes eat little fishes. Big eddies eat little eddies on Jupiter, and the little eddies are not coming in so he can grab them right now. So we think the red spot has gone on a diet.

The Great Red Spot may eventually begin growing again. Or it may stabilize at a smaller size. Or it could even disappear. About the only thing we can say for sure is that astronomers will keep an eye on it to see what happens.

Script by Damond Benningfield, Copyright 2014

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