Astronomers have discovered the first ever planet resembling the Earth around another star – and conditions could be ideal there for life. Observations show that oceans of water could cover the new Earth’s surface because it lies in the so-called “habitable zone” around its own sun.
Previous planets discovered beyond the solar system have all been giant gas balls like our own neighbour Jupiter. Water was recently detected in the atmosphere of one.
The new Earth-like planet is orbiting a red dwarf star called Gliese 581 in the constellation of Libra. It was spotted by European astronomers using a giant telescope on a mountaintop at La Silla, Chile, and is known as Gliese 581c.
I recently reported that Nasa say they have the computer technology to detect Earth-like worlds. The Gliese 581 discovery team did not use this technique. Neither did they glimpse the world directly but instead were able to measure its orbital velocity.
The planet is 14 times closer to its star than we are to our sun and zips round it in just 13 days. But the star is much cooler and less bright, say the astronomers, meaning conditions resemble those on Earth.
Gliese 581 is one of the closest stars to us, lying just 20.5 light-years away.
The discovery team, including Swiss, French and Portuguese scientists, are announcing their discovery today.
Their leader Stéphane Udry said: “We have estimated that the mean temperature of this super-Earth lies between 0 and 40 degrees Celsius, and water would thus be liquid. Models predict that the planet should be either rocky – like our Earth – or covered with oceans.”
Colleague Xavier Delfosse said: “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. On the treasure map of the universe, one would be tempted to mark this planet with an X.”
A giant planet similar in size to Neptune had previously been found around Gliese 581 and the astronomers suspect there is a third around eight times the weight of the Earth.
The picture is an ESO artist’s impression of the new Earth.