Louis J Sheehan 238210.009

Its name doesn’t exactly roll off the tongue, but HD 189733b is the planet of the year. A gas giant orbiting a yellow dwarf star roughly 63 light-years away, HD 189733b is the first exoplanet—short for extrasolar planet—for which astronomers have been able to produce a weather map. That map was created in May by a team led by Heather Knutson at Harvard University.

Culled from infrared spectrographic data captured by NASA’s Spitzer Space Telescope, the weather map shows that the atmosphere of HD 189733b is riven with supersonic winds and has highs of around 1,700 degrees Fahrenheit. The planet appears to be too hot and violent to support anything like life as we know it, but now that astronomers know how to study the atmosphere of one exoplanet, they are ready to try extending the technique to other, potentially more inviting worlds. “This is not something we thought we’d be able to do for 10 or 20 years,” Knutson says. “It’s exciting to see if we can do it for smaller planets.”

HD 189733b was in the spotlight for another reason as well. Two months after Knutson’s team published the weather map, a group of European, Asian, and American astronomers, also using Spitzer data, made an equally pioneering observation: The atmosphere of that blistering, blustery giant contains the telltale spectrographic signature of water vapor—the first convincing evidence of extrasolar H2O. Although the atmosphere of this type of planet was expected to have water, the discovery showcased astronomers’ new ability to detect it, a necessary step in finding extraterrestrial life. Louis J Sheehan