WASHINGTON, April 25: European astronomers have spotted what they say is the most Earth-like planet yet outside our solar system, with balmy temperatures that could support water and, potentially, life.
They have not directly seen the planet, orbiting a red dwarf star called Gliese 581. But measurements of the star suggest that a planet not much larger than the Earth is pulling on it, the researchers said in a letter to the editor of the journal Astronomy and Astrophysics.
“This one is the first one that is at the same time probably rocky, with water, and in a zone close to the star where the water could exist in liquid form,” said Stephane Udry of the Geneva Observatory in Switzerland, who led the study.
“We have estimated that the mean temperature of this super-Earth lies between zero and 40 degrees Celsius, and water would thus be liquid.”
The discovery came thanks to a highly sensitive instrument at the European Space Observatory’s facility at Silla, Chile.
Most of the 200 or so planets that have been spotted outside this solar system have been gas giants like Jupiter.
But this one is small.
“Its radius should be only 1.5 times the Earth’s radius, and models predict that the planet should be either rocky, like our Earth, or covered with oceans,” Udry said in a telephone interview.
“Because of its temperature and relative proximity, this planet will most probably be a very important target of the future space missions dedicated to the search for extra terrestrial life.”
It appears to have a mass five times that of the Earth’s.The new planet is 14 times closer to Gliese 581 than the Earth is to the Sun. But because Gliese 581 is so cool, the planet is not scorched by solar radiation. It zips around the star at express speed, making just 13 days to complete an orbit.
The research team includes scientists credited with the first widely accepted discovery of a planet outside our solar system, in 1995.
Many teams are looking for planets circling other stars.
They are especially looking for those similar to our own, planets that could support life.
That means finding water.
X MARKS THE SPOT: “Because of its temperature and relative proximity, this planet will most probably be a very important target of the future space missions dedicated to the search for extra-terrestrial life,” Xavier Delfosse, a member of the team from Grenoble University in France, said in a statement.
“On the treasure map of the universe, one would be tempted to mark this planet with an X.”
Gliese 581 is among the 100 closest stars to Earth, just 20.5 light-years away in the constellation Libra.
A light-year is the distance light travels in a year, about 10 trillion kilometres.
It is smaller and dimmer than the sun, so the planet can be close to it and yet not be overheated.
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