life outside Earth

An Earth-size planet has been spotted orbiting a nearby star at a distance that would makes it not too hot and not too cold — comfortable enough for life to exist, researchers announced (Sept. 29).

If confirmed, the exoplanet, named Gliese 581g, would be the first Earth-like world found residing in a star's habitable zone — a region where a planet's temperature could sustain liquid water on its surface.

And the planet's discoverers are optimistic about the prospects for finding life there.

"Personally, given the ubiquity and propensity of life to flourish wherever it can, I would say, my own personal feeling is that the chances of life on this planet are 100 percent," said Steven Vogt, a professor of astronomy and astrophysics at the University of California, Santa Cruz, during a press briefing today. "I have almost no doubt about it."

The star is located 20 light-years from Earth in the constellation Libra. One light-year is about 6 trillion miles (10 trillion km).

Red dwarf stars are about 50 times dimmer than our sun. Since these stars are so much cooler, their planets can orbit much closer to them and still remain in the habitable zone.

Estimates suggest Gliese 581g is close enough to its star to be able to complete an orbit in just under 37 days.

With support from the National Science Foundation and NASA, the scientists — members of the Lick-Carnegie Exoplanet Survey — collected 11 years of radial velocity data on the star. This method looks at a star's tiny movements due to the gravitational tug from orbiting bodies.

The subtle tugs let researchers estimate the planet's mass and orbital period, how long it takes to circle its star.

Gliese 581g has a mass three to four times Earth's, the researchers estimated. From the mass and size, they said the world is probably a rocky planet with enough gravity to hold onto an atmosphere.

Just as Mercury is locked facing the sun, the planet is tidally locked to its star, so that one side basks in perpetual daylight, while the other side remains in darkness. This locked configuration helps to stabilize the planet's surface climate, Vogt said.

But whether Gliese 581g harbors life may not be the most striking aspect of this find. Vogt says the discovery of a potentially habitable world less than 100 light-years away means that habitable worlds may be much more common than astronomers thought. Given the number of stars in the Milky Way, Vogt explains, that could mean there are "potentially billions" of Earth-like worlds out there.

With the vastness of the universe, and the innumerable possibilities of combinations, it seems to me that the existence of life outside Earth might be not only possible, but unavoidable.... What if this life has been only 1000 years ahead of us in development? If they have gone through the challenges and difficulties we are going through now? their consciousness has gone through the evolutionary shaping process? What would be the impact on us if we could eventually communicate with such forms of life? By the way, what is life? is it something that comes up from a certain environment and evolves interacting with the evolving environment? is it just a type of manifestation in the universe?, is it separate from it?......


(This artist's conception shows the inner four planets of the Gliese 581 system and their host star, a red dwarf star only 20 light years away from Earth. The large planet in the foreground is the newly discovered GJ 581g, which has a 37-day orbit right in the middle of the star's habitable zone and is only three to four times the mass of Earth, with a diameter 1.2 to 1.4 times that of Earth. Credit: Lynette Cook) (Text and image taken from www.space.com)