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Earth-like Planets Could Be Common

NewsMax.com Wires Wednesday, Feb. 21, 2001

SAN FRANCISCO (UPI) – Earth-like planets could be remarkably common, perhaps orbiting half of the 100 billion stars in our Milky Way galaxy, new research by a Canadian astronomer suggests.

Norman Murray, a researcher at Canadian Institute for Theoretical Astrophysics in Toronto, has studied the atmospheres of more than 600 nearby, sunlike stars. Many of them have such high concentrations of iron that they must be absorbing it from rocky material in the surrounding environment, he says. And if there's enough rock to feed those stars – some of them swallowing an amount equal to half the mass of the Earth – then there's enough material to have formed an abundance of Earth-like planets as well, Murray asserts.

The study provides "evidence that there is terrestrial-type material orbiting most of the stars in the solar neighborhood," said Murray. "So the implication, if this result holds up, is that there are Earth-like bodies in orbit around most of the stars in the galaxy."

Murray spoke at a symposium on planetary formation at this week's meeting of the American Association for the Advancement of Science. His paper has been submitted to the Astrophysical Journal.

"I think it's a fascinating idea. It's a very logical idea," said astronomer and planet expert Geoffrey Marcy of the University of California in Berkeley. "It's consistent with our understanding of how planets form."

More than 50 planets beyond our solar system have been discovered so far, but most of them are as large as Jupiter – the largest member of our own family of planets – and some weigh more than 10 Jupiters. Murray's theory offers the tantalizing possibility that smaller, Earth-like planets may be common as well. If that's true, and Murray's finding is far from solid proof, it would strengthen the argument that life could have evolved beyond Earth.

The study "indicates that terrestrial planets may well be very common," Murray said. "And if terrestrial planets are common, then that makes you think that it's more likely that life could have evolved in our galaxy around stars other than just our own."

However, Murray cautioned that his study does not yet prove the existence of terrestrial planets.

"This is a very indirect method," he said. "It's not a direct detection of these planets. It's a statistical method, so I could be fooled by irregularities in the sample that I'm examining."

Murray's study was supported by NASA and the Natural Sciences and Engineering Research Council of Canada.

Copyright 2001 by United Press International. All rights reserved.

-- Uncle Bob (unclb0b@aol.com), February 21, 2001