Group finds extrasolar planet habitable

World located 20.4 light years away could harbor life.
Scientists estimate that it is only slightly larger than Earth.

Artist's conception of habitable planet around Gliese 581. (Photo: ESO)

The search is finally over - or, in the words of the scientists themselves, it just got more interesting. A European group of researchers has discovered a planet outside our solar system that is much like Earth, with potential conditions to harbor life.

He is one of the three known planets orbiting a star called Gliese 581. This is a star of the most common of a class known as red dwarfs - smaller and cooler than the Sun The innermost planet is probably a gas giant, similar in size to Neptune, and completes an orbit around the star every 5.4 days on land. It was discovered two years ago.

The innovations are the other two planets, presented in a paper submitted to the journal "Astronomy and Astrophysics" (which was embargoed until this Tuesday 20h). The outermost one complete turn every 84 days and is about eight times the land mass. More interesting is that the middle planet. He has "only" five times the mass of the Earth (the smallest ever detected) and has a year that lasts a measly 13 days.

Although he is much closer to Gliese 581 than Earth's sun, as his star is much dimmer, its orbit falls into the so-called Zone of Habitability. It is the region in which a planet is not neither too hot nor too cold, and may harbor liquid water - essential to life main feature.

The group led by Michel Mayor of Geneva Observatory in Switzerland, estimates that the average temperature in this world is between 0 and 40 degrees Celsius - not unlike the Earth, whose average temperature is 15 degrees.

• Hunting data

The study of planets outside our solar system - there are more than the 200 known today - is still a delicate task. As they are very distant, it is impossible with current techniques, view the planet - the brightness of the star ends up overshadowing the parent. The most common strategy to detect them is to observe the star over time, trying to detect in its light, signs of movement.The idea is that while the planets revolve around the star, they draw from one side to the other, producing a stellar wobble. The detection of this wobble can be deduced that the planets would be needed to produce it.This was the technique used by Mayor and colleagues to detect the cousin closest to Earth today. The problem is that the data obtained with a telescope of ESO (European Southern Observatory) in Chile, do not say everything there is to know about this star. For example, it is possible to establish the mass, but the diameter (roughly the "width") of the world still depends on the chutômetro.Scientists estimate that the star has recently discovered about one and a half times the diameter of Earth (which would give a little less than 20,000 km).

• Cruel Questions

Everything else on this planet remains open. This includes, of course, the most essential features of this world. "We believe it is a rocky planet like Earth, with some oceans," said the G1, by telephone, Mayor. "However, some models suggest that it may be what is called 'ocean planet', with much more water than the Earth."

In the Solar System, there is no example of a planet-ocean. "But the theoretical models show that it could exist elsewhere," says Mayor. The key to this was that the planet to form farther away from the star, where there is more ice, and then migrate to the interior of the system. A nice portion of the total mass would create a global ocean, with many miles deep.Based on the information available, it is impossible to say whether the newly discovered star is most like Earth or a planet-ocean, but the fact is that in both cases, the presence of liquid water would be ensured. For most scientists, this is the basic precondition for the evolution of life.

Image shows the red dwarf star Gliese 581. (Photo: ESO)

• Good and bad news

Of course, between being able to have life and have it go a long distance. And astronomers say they will still need a few decades of research so that the instruments are capable of searching for "signatures" of life in the light of these objects.

The most eloquent conclusion, however, is that the discovery shows evidence that the universe must be full of planets like Earth. The star Gliese 581 is one of the hundred closest to the Sun It is 20.4 light years away - which is not so far away, in astronomical terms, is right there.

The fact that we found so similar neighbors already in the vicinity shows that they must be everywhere. Now it's just a matter of finding.

Via G1.