First signs of water seen on planet outside solar system
Email this storyPrint this story 5:00AM Thursday April 12, 2007
WASHINGTON - Evidence of water has been detected for the first time in a planet outside this solar system, an astronomer says.
The find is tantalising for scientists eager to know whether life exists beyond Earth.
Travis Barman, an astronomer at Lowell Observatory in Flagstaff, Arizona, said water vapour had been found in the atmosphere of a large, Jupiter-like gaseous planet located 150 light years from Earth in the constellation Pegasus. The planet is known as HD 209458b.
Other scientists reported in February that they were unable to find evidence of water in this planet's atmosphere, as well as another Jupiter-like planet.
"I'm confident," Mr Barman said. "It's definitely good news because water has been predicted to be present in the atmosphere of this planet and many of the other ones for some time."
Lowell Observatory, a privately owned astronomical institution, said the research, which has been accepted for publication in the Astrophysical Journal, was backed by Nasa.
The detection of the presence of water vapour was possible because this planet, from the vantage point of Earth, orbits directly in front of its star every 3 1/2 days, allowing crucial measurements to be made. It is what is known as a transiting planet.
Scientists searching for signs of life beyond Earth are keen to learn about the presence of water on other planets - in and beyond this solar system - because water is thought to be fundamental to the existence of life.
Mr Barman noted that a Jupiter-like gaseous planet such as this one, as opposed to a rocky one like Earth, was highly unlikely to harbour life, saying the finding about water vapour in its atmosphere did not answer one way or another questions about the existence of extraterrestrial life.
The findings "are not adequate to really address a question as deep and profound as the existence of life elsewhere. We're not there yet.
"Certainly this is part of that puzzle - understanding the distribution of water in other solar systems is important for understanding whether or not conditions for life are possible. The presence of water does not exclude the possibility of life but it doesn't mean it's there, either."
Mr Barman said his findings did provide good reason to believe other planets beyond this solar system also had water vapour in their atmospheres.
Water has been found elsewhere in this solar system such as in large deposits of ice at the north and south poles of Mars.
Planet HD 209458b was also the first planet outside this solar system found to have an atmosphere.
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