Scientists taking their first „sniffs of air“ from planets outside our solar system are a bit baffled by what they did not find: water. One of the more basic assumptions of astronomy is that the two distant, hot gaseous planets they examined must contain water in their atmospheres. The two suns the planets orbit closely have hydrogen and oxygen, the stable building blocks of water. These 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. But when two different teams of astronomers used NASA’s Spitzer Space Telescope for this new type of extrasolar planet research, they both came up dry, according to their studies published in Thursday’s edition of „Nature“ and the online version of the „Astrophysical Journal Letters“. The study of one planet found hints of fine silicate-particle clouds. Research on the other planet found no chemical fingerprints for any of the molecules scientists were seeking.
So far, scientists have found 213 planets outside our solar system, but only 14 have orbits that make it possible for this type of study; only eight or nine of those are close enough to see. One team studied the closest, which goes by the catchy name HD 189733b. It is about 360 trillion miles from Earth in the constellation Vulpecula. The other planet, HD 209458b, studied by the other team, is about 900 trillion miles away in the constellation Pegasus and it is the one with the strange silicate clouds.
NASA’s Spitzer First To Crack Open Light of Faraway Worlds