Original URL: http://www.theregister.co.uk/2007/05/10/nasa_exoweather/

Spitzer stargazers find hot, windy planets

NASA does exo-weather

By Lucy Sherriff

Posted in Science, 10th May 2007 00:26 GMT

NASA has moved into extra-solar planetary weather forecasting. Well, mapping, but one has to start somewhere. Researchers using the agency's Spitzer infrared space telescope have mapped the weather patterns of two extremely hot, distant planets.

The May 9th edition of Nature carries a description of the winds on the surface of a gas giant known as HD 189733b (ah, the romance) and the discovery that gas giant HD 149026b is the hottest ever discovered. In the interests of keeping your attention, we're going to rename the two planets Windy and Spicy, respectively, for the duration of the article.

"We have mapped the temperature variations with longitude across the entire surface of a planet that is so far away, its light takes 60 years to reach us," said Heather Knutson of the Harvard-Smithsonian Center for Astrophysics, lead author of the paper describing Windy.

The planet Windy is located 60 light-years away in the constellation Vulpecula. It orbits its host star in a speedy 2.2 days, happily passing between the star and the Earth, giving astronomers the best possible view.

The researchers took roughly a quarter of a million measurements of the planet's face in the infrared, and built them up into a map of the entire surface.

They discovered that the planet is a perfectly delightful 1,200 F on the dark side to 1,700 F on the sunlit side. (Yes, this is Windy, not Spicy.) The relatively small variation in temperature from one side of the planet to the other suggests that the atmosphere must be whipped around the planet on jet stream winds reaching as much as 6,000mph.

Spicy, meanwhile, is even hotter, checking in at a seriously melting 3,700 F. The planet is located 279 light-years away in the constellation Hercules. It is the smallest and densest known transiting planet, with a size similar to Saturn's and a core suspected to be 70 to 90 times the mass of Earth.

Joseph Harrington of the University of Central Florida said: "This planet is like a chunk of hot coal in space. We believe its heat is not being spread around. The day side is very hot, and the night side is probably much colder."

Harrington added that the planet reflects virtually no starlight. This, he says, means that it is probably the blackest body ever found, as well as the hottest. ®