First Sign of Water on Planet Outside Our System

<< Back to Page 1   Page 2 of 2

Some of the more recently discovered planetary systems may be better candidates for such analysis, Barman said. But, he added, Hubble captured data from HD209458b with an instrument that is no longer working—so the particular kind of measurement used is no longer possible for other systems using Hubble.

Hot Jupiters

The mass of planet HD209458b is 220 times greater than Earth's. Like Jupiter, HD209458b is a gaseous planet, though it is only about seven-tenths the mass of our solar system's largest planet.

HD209458b orbits its star more closely than Mercury orbits our sun.

These traits put it into a class with other so-called hot Jupiters, which make up about 40 percent of known planets orbiting other stars. (Related: "'Hot Jupiters' Could Give Rise to Earthlike Worlds, Study Says" [September 7, 2006].)

Astronomers are interested in hot Jupiters because their size makes them the easiest exoplanets to study—and because their violent gravitational dynamics may both create and destroy Earth-size planets.

Jeremy Richardson, of NASA's ExoPlanets and Stellar Astrophysics Lab in Maryland, was lead author of an HD209458b report in the journal Nature in February.

Richardson's study found no evidence of water in the atmosphere.

But he said his team's observations were made using different techniques than Barman's—so they're not necessarily contradictory.

"The Barman paper looks at observations taken during transit," Richardson said.

"Our observations were made just before the planet disappears behind the star."

Other scientists, he said, have suggested that winds can obscure signs of water at this stage of a planet's orbit.

Free Email News Updates
Best Online Newsletter, 2006 Codie Awards

Sign up for our Inside National Geographic newsletter. Every two weeks we'll send you our top stories and pictures (see sample).

<< Back to Page 1   Page 2 of 2




NEWS FEEDS     After installing a news reader, click on this icon to download National Geographic News's XML/RSS feed.   After installing a news reader, click on this icon to download National Geographic News's XML/RSS feed.

Get our news delivered directly to your desktop—free.
How to Use XML or RSS

National Geographic Daily News To-Go

Listen to your favorite National Geographic news daily, anytime, anywhere from your mobile phone. No wires or syncing. Download Stitcher free today.
Click here to get 12 months of National Geographic Magazine for $15.