Earth-like planets in our galactic neighbourhood

Earth-like planets with life-sustaining conditions are spinning around stars in our galactic neighbourhood, US astrophysicists say. They just haven't been found yet.

"There are something like a few dozen solar-type stars within something like 30 light years of the sun, and I would think that a good number of those -- perhaps half of them have Earth-like planets," Alan Boss told the annual meeting of the American Association for the Advancement of Science (AASS).

"So I think there is a very good chance that we will find some Earth-like planets within 10, 20 or 30 light years of the Sun," the astrophysicist from the Carnegie Institution for Science told his AAAS colleagues meeting here since Thursday.

One light year equals the distance light travels in one year at the speed of 300,000 kilometers (186,000 miles) per second, or 9.46 trillion kilometers (5.88 trillion miles).

Boss is convinced that the Earth-sized planets could be found either by the Kepler space telescope US space agency NASA plans to launch on March 5, or by the French-European telescope-equipped COROT satellite that has been in orbit since 2006.

"I will be absolutely astonished if Kepler or COROT didn't find any earth-like planets, because basically we are finding them already," Boss told a press conference Saturday when asked why he felt so confident.

COROT has already discovered the smallest extraterrestrial planet so far. At a little over twice the Earth's diameter, the planet is very close to its star and very hot, astronomers reported earlier this month.

Boss said Kepler and COROT will likely find so many Earth-like planets that they will "tell us how to go ahead and build the next space telescope to go and examine these planets, after we know they are there."

The images from those new planets, he added, should identify "light from their atmosphere and tell us if they have perhaps methane and oxygen. That will be pretty strong proof they are not only habitable but actually are inhabited."

"I am not talking about a planet with intelligence on it. I simply say if you have a habitable world ... sitting there, with the right temperature with water for a billion years, something is going to come out of it.

"At least we will have microbes," said Boss.

Raymond Jeanloz, professor of astronomy, earth and planetary science at the University of California at Berkeley, delved further into the matter.

"I can strongly reinforce Alan Boss's point that life from this perspective that is very much driven by our understanding from the genome, is in some sense 'inevitable,'" if the same basic building blocks of life that exist on Earth are present.

"The distinction will be more between a class of life form that can communicate with us versus ... the vast abundance of life forms recorded in our fossil records, namely microbial life."

On the possibility of finding an extra-terrestrial civilization, Boss said the research "is an interesting one and an important one to do because, even though there is a small probability of success, if you actually find something, it is an immense discovery to make.

"So you say, 'yes, this is worth doing.'"