When a probe from the Galileo spacecraft took its death plunge into Jupiter’s atmosphere last December, it was buffeted by 400-mile-an- hour winds some 80 miles below the giant planet’s cloud tops. These winds aren’t easy to explain. Winds on Earth are generated by the heat of the sun. But solar heat can’t penetrate very far into Jupiter’s thick clouds. Even before Galileo reached Jupiter, astronomers wondered what was driving such turbulent Jovian weather systems as the huge storms we see as the Great Red Spot and the bands of clouds roiling through the planet’s atmosphere. Some suspected the existence of an internal heat source-- perhaps energy released by the gravitational compression of gases deep within the planet. That theory has just gotten a boost: two astronomers have simulated Jupiter’s distinctive bands using a scale model of the planet.
The model consists of a copper shell nested inside a foot-wide ...
