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.
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.
This exciting discovery was made using NASA's Spitzer Earth-orbiting telescope, taking measurements at a number of key wavelengths in the infrared region of the spectrum that pick out the crucial signature of water.
The water detection relied not only on Dr Tinetti's painstaking analysis, but also on the calculation of highly accurate water absorption parameters by Bob Barber and Professor Jonathan Tennyson, also from UCL.
"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, who is taking up a prestigious STFC (Science and Technology Facilities Council) Aurora Fellowship at UCL to study atmospheric signatures and biosignatures on planets beyond our solar system, was quoted as saying.
"Initial data included over 500 million individual absorption features and from this we calculated the absorption parameters. Each feature is unique, like a fingerprint, and provides vital clues about the amount of water present and the temperature of the atmosphere," said Barber.
Commenting on this result, Professor Keith Mason, CEO of the STFC, said this first conclusive evidence of the presence of water vapor in the atmosphere of a planet beyond our Solar System provides "an exciting breakthrough in our knowledge of extra-solar planets," representing a real step forward into establishing whether we are alone in the universe or whether there is life on other planets.
Over 200 extra-solar planets are now known to exist, orbiting stars close to the sun.
Source: Xinhua
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