Earth-Like Planet Found

The first time astronomers have discovered a planet outside our solar system that is potentially habitable, with Earth-like temperature.

The find by 11 European researchers was described as a big step in the search for "life in the universe".

The planet is just the right size, might have water in liquid form, and in galactic terms is relatively nearby at 120 trillion miles away.

But the star it closely orbits, known as a "red dwarf," is much smaller, dimmer and cooler than our sun.

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 its sun-like 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 will likely be a lot like Earth"s not too hot, not too cold.

And that "just right" temperature is one key reason astronomers think this planet could conceivably house life outside our solar system.

It"s also as close to Earth-sized as telescopes have ever spotted. Both elements make it the first potentially habitable planet besides Earth or Mars.

Astronomers who announced the discovery of the new planet 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. "It"s a nice discovery. We still have a lot of questions."

There"s still a lot that is unknown 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 and Astrophysics.

Alan Boss, who works at the Carnegie Institution of Washington where a US team of astronomers 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 as Earth"s.

Its discoverers aren"t certain if it is rocky like Earth or if its a frozen ice ball with liquid water on the surface.

If it is rocky like Earth, which is what the prevailing theory proposes, it has a diameter about 11/2 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 and 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.