Water Discovered On Extra-solar Planet

An international team of scientists using NASA's Spitzer Space Telescope have discovered water on an extra-solar planet for the first time, the science magazine Nature reported Thursday, 12 July, 2007.
The planet with water in its atmosphere is known as HD189733b, and orbits a star in the constellation of Vulpecula, 63 light years from Earth, according to the report.
Planet HD189733b, a gas giant about 15 percent bigger than Jupiter, is known as a "transiting planet" as it passes directly in front of its star, as viewed from the Earth.
Unlike Jupiter, which is over five times as far away from the Sun as the Earth is, HD189733b is over 30 times closer to its star than the Earth is to the Sun - which is why it is so hot.
The researchers, led by Giovanna Tinetti, an ESA (European Space Agency) fellow from the Institute d'Astrophysique de Paris and University College London (UCL), found that HD189733b absorbs the starlight of its "sun", as it passes in front of it, in a way that can only be explained if it has water vapor in its atmosphere.
This is the first time that astronomers have demonstrated for certain that water is present in an extra-solar planet with the infrared analysis of the planet's transit across its parent star providing the breakthrough.
"Although HD189733b is far from being habitable, and is actually quite a hostile environment, our discovery shows how water might be common out there and how our method can be used in the future to study more life-friendly environments," Tinetti said.