Wednesday, February 21, 2007

Distant Planets: Warm, Weird, Waterless

The first indicators of atmospheric makeup 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.

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.

The two suns the planets orbit closely have hydrogen and oxygen, the stable building blocks of water. The planets' atmospheres are supposed to be made up of the same thing, good old H2O.

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.

How hot? Try 1,500 degrees Fahrenheit. How windy? Somewhere between 500 and 2,000 mph. Scientists studying these extrasolar planets agree that not finding water where it was expected is a wake up call for more research.

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