Newly discovered planet all steamed up.

• Position: Hubble Telescope - Designated HD209458b planet - Brief article

The powerful vision of NASA's Hubble Space Telescope has allowed astronomers to study for the first time the layer-cake structure of the atmosphere of a planet orbiting another star. Hubble discovered a dense upper layer of hot hydrogen gas where the super-hot planet's atmosphere is bleeding off into space.

This newly found planet, designated HD209458b, is unlike any world in our solar system. It orbits so close to its star and gets so hot that its gas is streaming into space, making the planet appear to have a comet-like tail. Research has revealed the layer in the planet's upper atmosphere where the gas becomes so heated it escapes like steam rising from a boiler.

"The layer we studied is actually a transition zone where the temperature skyrockets from about 1,340[degrees]F to about 25,540[degrees]F, which is hotter than the sun," explains Gilda Ballester of the University of Arizona, Tucson, leader of the research team. "With this detection, we see the...