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NASA Telescopes Zero in on Two Huge Distant Planets

Posted on: Saturday, 26 March 2005, 12:00 CST

A NASA telescope peering far beyond our solar system has for the first time directly measured light from two Jupiter-sized gas planets closely orbiting distant stars, adding crucial features to astronomy's portrait of faraway worlds.

Studies of the infrared light streaming from the two giant planets suggest that they are made of hot, swirling gases that reach a broiling 1,340 degrees Fahrenheit or higher.

"It's an awesome experience to realize we are seeing the glow of distant worlds," said David Charbonneau of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., whose astronomy team captured light from a planet in the constellation Lyra. "The one thing they can't hide is their heat."

Since the mid-1990s, scientists have discovered more than 130 of these so-called extrasolar planets. But the stars they orbit are so distant and shine so brightly that they tend to overwhelm the planets from view.

To find them, astronomers indirectly measure the tiny gravitational wobble that planets exert on their suns, or the brief dimming of starlight that occurs when a planet's orbit moves it in front of the star.

But hot celestial objects such as these gas planets also emit infrared light. NASA's Spitzer Space Telescope has detectors to collect these infrared signals. Infrared light contains specific signatures in different wavelengths that reveal more scientific characteristics about a space object than visible light.

One planet, known as HD 209458b and nicknamed Osiris, orbits a sun-like star 150 light-years from Earth in the constellation Pegasus. Its infrared signature was measured at NASA's Goddard Spaceflight Center in Greenbelt, Md. Details will appear Wednesday in the online version of the journal Nature.

The other extrasolar planet measured by the Harvard-Smithsonian team is known as TRes-1. It is 500 light-years from Earth in the constellation Lyra. Results will be published in the June 20 issue of Astrophysical Journal.

Source: Tulsa World

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