dang global warming on planet 209458

[Guest guest]

http://news./s/ap/20070221/ap_on_sc/dry_planets

Distant planets: Warm, weird, waterless

By SETH BORENSTEIN, AP Science Writer Wed Feb 21, 6:03 PM ET

WASHINGTON - The first " sniffs of air " of two huge far-away planets

reveal that they seem to be missing water, a surprising finding amid

weather unlike any planets in our solar system with blast furnace-like

gusts amid supersonic winds.

The absence of water from the atmosphere of both these Jupiter-sized

gaseous bodies upsets one of the most basic assumptions of astronomy.

One of the researchers, Harvard University astronomy professor

Charbonneau, called the planets " very different beasts ... unlike any

other planets in the solar system. "

So far, scientists have found 213 planets outside our solar system †"

they are called exoplanets. But only eight or nine are in the right

orbit and location for the type of study reported by three teams using

NASA's Spitzer Space Telescope.

The closest of the two planets studied, HD 189733b, is 360 trillion

miles from Earth in the constellation Vulpecula. The other planet, HD

209458b, is about 900 trillion miles away in the constellation Pegasus

and it has a strange cloud of fine silicate particles. Two different

research teams studied it.

The two suns the planets orbit closely have hydrogen and oxygen, the

stable building blocks of water. The planets' atmospheres †" examined

for the first time using light spectra to determine the air's chemical

composition †" are supposed to be made up of the same thing, good old H2O.

" We had expected this tremendous signature of water ... and it wasn't

there, " said Carl Grillmair of the California Institute of Technology

and Spitzer Science Center. He and Charbonneau studied the closer of

the two planets, and their work is being published online in The

Astrophysical Journal Letters.

Our own solar system has two planets without water in the atmosphere,

Grillmair noted: Mercury, which doesn't have an atmosphere, and Venus,

which is a different type of planet from the huge gaseous ones that

would be expected to have the components of water in the air.

But consider the atmosphere on the second of the two exoplanets, the

one 900 trillion miles away: " Weather today on 209458 is hot, dry,

probably cloudy with a chance of wind, " study team leader Mark Swain

of NASA's Jet Propulsion Lab said in a Wednesday teleconference.

How hot? Try 1,500 degrees Fahrenheit. How windy? Somewhere between

500 and 2,000 mph.

Another research team found indications that the atmosphere has grains

of silicon-oxygen compounds. That team, led by L. of

NASA's Goddard Space Flight Center in land, is reporting its

research in Thursday's issue of Nature.

But the key finding is dry.

" In NASA's search for life beyond Earth, the mantra has been to follow

the water, " said Carnegie Institution of Washington astronomer Alan

Boss, who wasn't involved in any of the research.

Scientists say it's possible the water is hiding beneath dust clouds

or that all the airborne water molecules are the same temperature,

making it impossible to see using an infrared spectrograph. Or maybe

it's just not there and astronomers have to go back to the drawing

board when it comes to these alien planets.

" The very fact that we've been surprised here is a wake-up call. We

obviously need to do some more work, " Grillmair said.

Charbonneau said these surprising " sniffs of air from an alien world "

tell astronomers not to be so Earth-centric in thinking about other

planets. " We're limited by our imagination in thinking about the

different avenues that these atmospheres take place in, " he said.

Swain called the results " a very important stepping stone for our

ultimate goal of characterizing planets around other stars where life

could exist. "

___