HOUSING IN SEATTLE IS GETTING EXPENSIVE, WANT TO LIVE ON ANOTHER PLANET

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Wednesday, April 25, 2007
Last updated 8:08 a.m. PT
New planet
AP
This artist's rendering, released by European Southern Observatory, shows the planetary system around the red dwarf Gliese 581.
Life in a galaxy not so far, far away?
Astronomers discover new, Earth-like planet

By SETH BORENSTEIN
THE ASSOCIATED PRESS

WASHINGTON -- European astronomers have found the most Earth-like planet outside our solar system, and here's what it might be like to live there:

The "sun" wouldn't burn brightly. It would hang close, large and red in the sky, glowing faintly like a charcoal ember. And it probably would never set if you lived on the sunny side of the planet.

You could have a birthday party every 13 days because that's how fast this new planet circles that sunlike star. But watch the cake -- you'd weigh a whole lot more than you do on Earth.

You might be able to keep your current wardrobe. The temperature in this alien setting likely will be a lot like Earth's -- not too hot, not too cold.

That "just right" temperature is one key reason astronomers think this planet could conceivably house life outside our solar system. The planet is also as close to Earth-sized as telescopes have ever spotted, might have water in liquid form and in galactic terms is relatively nearby -- all elements that make it the first potentially habitable planet besides Earth or Mars.
Illustration

Astronomers who announced the discovery Tuesday say this puts them closer to answering the cosmic question: Are we alone?

"It's a significant step on the way to finding possible life in the universe," said University of Geneva astronomer Michel Mayor, one of 11 European scientists on the team that found the new body. "It's a nice discovery. We still have a lot of questions."

There are still a lot of unknowns about the new planet, which could be deemed inhospitable to life once more is learned about it. But as galaxies go, it's practically a neighbor. At only 120 trillion miles away, the red dwarf star that this planet circles is one of the 100 closest to Earth.

The results of the discovery have not been published but have been submitted to the journal Astronomy & Astrophysics.

Alan Boss, who works at the Carnegie Institution of Washington where a U.S. team competed in the hunt for an Earth-like planet, called it "a major milestone in this business."

The planet was discovered by the European Southern Observatory's telescope in La Silla, Chile, which has a special instrument that splits light to find wobbles in different wavelengths. Those wobbles can reveal the existence of other worlds.

What they revealed is a planet circling the red dwarf star Gliese 581. Red dwarfs are low-energy, tiny stars that give off dim red light and last longer than stars like our sun. Until a few years ago, astronomers didn't consider these stars as possible hosts of planets that might sustain life.

The discovery of the new planet, named 581 c, is sure to fuel studies of planets circling similar dim stars. About 80 percent of the stars near Earth are red dwarfs.

The new planet is about five times heavier than Earth, and gravity there would be 1.6 times as strong. Its discoverers aren't certain if it is rocky like Earth or if it's a frozen ice ball with liquid water on the surface. If it is rocky like Earth, the prevailing theory, it has a diameter about 1 1/2 times bigger than our planet. If it is an iceball, as Mayor suggests, it would be even bigger.

Based on theory, 581 c should have an atmosphere, but what's in that atmosphere is still a mystery and if it's too thick that could make the planet's surface temperature too hot, Mayor said.

However, the research team believes the average temperature to be somewhere between 32 and 104 degrees -- a finding that set off celebrations among astronomers.

Until now, all 220 planets astronomers have found outside our solar system have had the "Goldilocks problem." They've been too hot, too cold or just plain too big and gaseous, like uninhabitable Jupiter.

The new planet seems just right -- or at least that's what scientists think.

Eventually astronomers will rack up discoveries of dozens, maybe even hundreds of planets considered habitable, the astronomers said. But this one -- simply called "c" by its discoverers when they talk among themselves -- will go down in cosmic history as No. 1.

Besides having the right temperature, the new planet is probably full of liquid water, hypothesizes Stephane Udry, the discovery team's lead author and another Geneva astronomer. But that is based on theory about how planets form, not on any evidence, he said.

Other astronomers cautioned it's too early to tell whether there is water.

"I expect there will be planets like Earth, but whether they have life is another question," said renowned astrophysicist Stephen Hawking in an interview with The Associated Press in Orlando. "We haven't been visited by little green men yet."

The new planet's star system is a mere 20.5 light years away, making Gliese 581 one of the 100 closest stars to Earth.

Still, said retired NASA astronomer Steve Maran, press officer for the American Astronomical Society, "We don't know how to get to those places in a human lifetime."

But, oh, the view, if you could.