Distant Planet Mapped for First Time, "Hot Jupiter" Features Fierce Winds

May 9, 2007

Giant planets known as hot Jupiters are even hotter, wilder, and more mysterious than scientists expected, two new studies reveal.

The studies include the first rough map ever completed of a planet outside our solar system.

Hot Jupiters are large, typically gaseous planets that orbit their stars much more closely than Jupiter circles the sun. (See an interactive map of the solar system.)

One of the new studies shows that fierce, hot winds on a hot Jupiter 63 light-years away sweep heat from the planet's daylight side to its dark, nighttime side.

(Read related story: "'Hot Jupiters' Could Give Rise to Earthlike Worlds, Study Says" [September 7, 2006].)

The other study suggests that another, even more distant hot giant is as black as coal and absorbs nearly all the light that hits it, re-emitting the energy as extraordinary heat.

The pitch-black world, the smallest known planet outside our solar system, is also one of the hottest: a whopping 3,500 degrees Fahrenheit (1,925 degrees Celsius), the study found.

Both studies appear in this week's issue of the journal Nature.

Keeping the Cool Side Hot

Because hot Jupiters are so close to—and always have one side facing—their stars, most scientists have expected that dramatic temperature differences would exist between the worlds' daylight, or star-facing, sides and their nighttime sides.

To test this theory, Harvard University graduate student Heather Knutson and her colleagues observed a hot Jupiter in the constellation Vulpecula using the Spitzer Space Telescope. They then used that data to develop a temperature map of the planet's surface.

The team found only a relatively minor difference in temperature—about 500 degrees Fahrenheit (280 degrees Celsius)—between the day and night sides.

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