Fortunately for hot-spot lovers, the Galileo probe entered one of these clearings when it was dropped from the Galileo spacecraft in 1995 -- after travelling some 600 million miles (960 million kilometers) from Earth to Jupiter and its moons. "We got a lucky break," said Glenn Orton, a planetary scientist at NASAs Jet Propulsion Laboratory. "Our data was taken in one of the clearest and driest regions on the planet."

Now, more recent analyses of data from the Galileo probe have shown that the drop was a great success. In fact, the mission gave planetary experts Adam Showman of NASAs Ames Research Center and Timothy Dowling of the University of Louisvilles Comparative Planetology Laboratory enough data to theorize on just whats going on at Jupiters hot spots. Their work is discussed in this weeks issue of the journal Science.

According to Dowling, the two researchers found that Jovian hot spots are associated with large-scale changes in wind speed at Jupiters middle latitudes. However, after analyzing data from a series of experiments conducted by the probe and modeled in a computer, they concluded that although hot spots represent an interesting portion of Jupiters atmosphere, information gathered from Galileos descent did not represent atmospheric patterns for the entire planet.

"We found that the Galileo probe profile of wind speed may only apply to the entry point and not to the whole planet," said Dowling. "So the picture is different depending on location."

Indeed, hot spots are just one type of feature found in the planets cloudy, windy and often stormy atmosphere. But they represent an interesting topic of study for scientists who have few chances to get up close and personal with Jupiters inner layers. "Hot spots represent very different dynamical phenomena than we see in the rest of the planet," said Orton. "But they represent opportunities to see quite deep in the atmosphere."

Because Jupiter has an internal heat source, hot hydrogen- and helium-rich air rises from the planets lower depths, then condenses out to form wet clouds and rain. But the air doesnt just sit there it also forms clearer, cool air at the atmospheres upper layers.

This combination of cool dry air with warm wet air makes Jupiters atmosphere a perfect place for crazy weather patterns. In some regions the air is moving away from the planet, condensing to form huge clouds (like the famous Great Red Spot) and light-colored bands. In other regions, the air is moving closer to the planets center, creating dark belts and even darker hot spots.