Mike
First habitable 'Earth-like' planet found
Temperature between 0 and 40c, scientists say
Margaret Munro, CanWest News Service
Published: Wednesday, April 25, 2007
Astronomers have spotted "the first habitable Earth-like planet" outside the solar system, a find so enticing that Canada's space telescope is being redirected to take a closer look.
The "super-Earth" appears to be 50% larger than Earth and orbiting around a star in a "habitable zone" where temperatures are so balmy that water -- the elixir of life-- would be liquid.
"We have estimated that the mean temperature of this super- Earth lies between 0C and 40C, and water would thus be liquid," said Stephane Udry, of the Geneva Observatory, who leads the European team that reported the discovery yesterday in the journal Astronomy and Astrophysics.
The planet, believed to be either rocky like Earth or covered with oceans, is seen as a promising target in the search for extraterrestrial life.
"On the treasure map of the universe, one would be tempted to mark this planet with an X," said team member Xavier Delfosse of Grenoble University.
Since the discovery in 1995 of the first "exoplanet" orbiting a star other than the sun, more than 200 planets have been found. Most are gas giants on extreme orbits around stars that make them either scorching hot or far too cold to maintain life as we know it.
The Europeans say the new planet is the smallest exoplanet and "most Earth-like" so far. They have deduced that it orbits its star in 13 days and is 14 times closer to its star than the Earth is to the sun.
The scientists found the planet using a super-sensitive planet-hunting machine fitted onto a European telescope in Chile. It detects the tiny changes -- or wobbles -- produced as planets orbit around stars. The planet's host star, a red dwarf called Gliese 581, is much smaller and colder than the sun, which means the planet can be close to its star but still be in the so-called "habitable zone," the region around a star where water would be liquid.
Canadian astronomer Jaymie Matthews of the University of British Columbia cautioned there is no evidence so far showing the planet actually harbours water, let alone "extras from Star Trek." All scientists can say for certain is the planet appears to exist, and could have a solid surface and habitable temperatures.
But the European evidence is so exciting, Mr. Matthews said, that he and his colleagues have agreed to focus Canada's suitcase-sized space telescope, known as MOST, on the alien solar system.
"We're putting it on a stakeout," said Mr. Matthews, who leads the MOST team and is currently in Vienna. (MOST stands for microvariabilty and oscillations of stars.)
He expects to have the planetary system in the microsatellite telescope's sights by late next week. "We've been working on this for a few weeks," he said in a phone interview.
Mr. Matthews said it will be possible to look for the "super-
Earth" without too big an impact on other MOST projects.
"We'll be squeezing it into to our regularly scheduled programming. That's the beauty of having something like MOST. It's almost like having your own private space telescope in the sense that it's possible for us to take advantage of these targets of opportunity and adapt very, very quickly."
With luck, Mr. Matthews said MOST, which has a much clearer view from its orbit above Earth, will be able to actually see the planet orbiting across the face of the star and confirm its existence.
The odds that MOST will be in the right vantage point to observe such a "transit" is about one in 20.
"It's a long shot," he said, but well worth taking because the results could be huge.
Wow. Just... Wow.
