Two wide stripes—known as the equatorial belts—normally circle the huge planet, products of the fast-moving jet streams that roar through Jupiter's atmosphere.

But pictures of Jupiter taken by an amateur astronomer show that sometime during the past couple weeks, the south equatorial belt completely faded from view.

"The basic view of Jupiter is of two dark belts. Now there is only one," said Alan MacRobert, senior editor of Sky & Telescope magazine.

"This is the most obvious change on Jupiter that I can recall," he said, adding that anyone with a backyard telescope should be able to see the difference. "Any instrument powerful enough to show any of Jupiter's surface features will easily reveal the change."

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