If the weather on Uranus, examined here yesterday, isn’t exotic enough for your taste, consider the situation on Jupiter-class worlds around other stars. A ‘hot Jupiter’ orbiting extremely close to its star spawns weather like nothing we’ve ever experienced, as modeled by computer simulations coming out of the University of Arizona. And while we can’t actually image these objects yet, we can certainly deduce a great deal about them from observations made during the times they transit their star.

On that score, well-studied HD 189733b is an early example of pushing the envelope. Located 63 light years from Earth, this transiting planet orbits once every 2.2 days, scooting along a mere three million miles from its primary. Spitzer Space Telescope data culling variations in starlight during the frequent planetary transits have allowed us to peg daytime temperatures on worlds like these, usually in a range somewhere between 2000 and 3000 degrees Fahrenheit (1300 and 1900 degrees Kelvin). What stands out in studies of HD 189733b, though, is the nightside, where temperatures reach almost 1300 degrees Fahrenheit (1000 degrees Kelvin) despite the obvious lack of light.

Considering how close this planet is to its star, that nightside reading is deeply interesting. It implies a robust heat transfer mechanism in the form of strong winds, a finding that may be generalized across the entire family of hot Jupiters. Much work has already gone into this. Have a look, for example, at this story on David Charbonneau’s work on HD 189733b’s atmosphere, followed by Geneva studies by Frédéric Pont that seem to identify haze there. Adam Showman (University of Arizona), who led the work we’re looking at today, is now producing the computer models that firm up the hot Jupiter picture. Says Showman:

“These planets are 20 times closer to their star than Earth is to the Sun, and so they are truly blasted by starlight… Because these planets are so close to their stars, we think they’re tidally locked, with one side permanently in starlight and the other side permanently in darkness. So, if there were no winds, the dayside would be extremely hot and the nightside would be extremely cold.”

Showman’s group performed 3-D simulations that factored in the absorption of all that blazing starlight and the ways in which a planet loses heat to space. The models explain the observed data for HD 189733b and suggest the kind of winds we’re talking about — jet streams with speeds reaching over 11,000 kilometers per hour. Winds like that, moving from west to east, push the hottest regions on the planet away from the ‘high noon’ region, Showman adds, and move them further east by about thirty degrees of longitude.

And I used to think that Venus was a good description of hell… Maybe it still is, but ‘hot Jupiters’ with supersonic winds and dayside temperatures that would melt lead now seem an even better way to view it. In any case, note the considerable distance we’re moving from early exoplanet work, which produced the first mass and orbital information about these distant worlds. Now we’re actually looking at planetary weather patterns for objects we cannot yet see directly. The science of exoplanet mapping is indeed in its infancy, but great things are coming.