A 'new Earth' 20 light years away

"Liquid water is critical to life as we know it. On the 'treasure map' of the Universe, one would be tempted to mark this planet with an X." - DR XAVIER DELFOSSE

Story in full AN EARTH-LIKE planet which could be covered in rivers, lakes and oceans and may support life has been discovered outside the solar system.

The new world, 20.5 light years away, orbits a region with the right temperature to allow liquid water on its surface.

Scientists believe it is only one-and-a-half times larger and five times more massive than Earth, making it the smallest known extra-solar planet.

But the really exciting discovery is that the planet is in the habitable zone of its parent star, Gliese 581. Also known as the "Goldilocks zone", this is the narrow orbit in which temperatures are not too hot, not too cold, but just right for surface water to exist as a liquid.

The habitable zone varies according to the star's heat output, and Gliese 581 is much smaller and colder than the Sun. So, even though the planet - known only as Gliese 581 C - is 14 times closer to the star than the Earth is to the Sun, it lies in a region where rivers and oceans are possible.

Dr Stephane Udry, from the Geneva Observatory in Switzerland, who led the European astronomers who announced the find yesterday, said: "We have estimated that the mean temperature of this super-Earth lies between zero and 40C, and water would thus be liquid. Its radius should be only 1.5 times the Earth's radius, and models predict the planet should be either rocky - like our Earth - or covered with oceans."

The vast majority of planets already discovered orbiting stars outside the solar system are giant gaseous worlds the size of Jupiter or bigger. Life as we know it could not exist on these.

But the new planet is highly unusual because it is so small, and therefore probably rocky. Given its size and location, it is likely to have an atmosphere. Scientists have also calculated the planet has about double the Earth's gravity. Any creatures living there would, be twice as heavy as they would be on Earth.

The planet, which has a 13-day orbit - or year - was discovered using the European Southern Observatory's 3.6-metre telescope at La Silla in Chile.

Astronomers employed a method of long-distance planet-finding that looks for the "wobble" on a star caused by the gravity of a large object orbiting it.

By measuring the wobble motion, shown as shifts in the star's light spectrum, astronomers are able to calculate a planet's orbit and mass. Gliese 581 C is certain to be a key target for future missions dedicated to the search for extra-terrestrial life.

"Liquid water is critical to life as we know it," Dr Xavier Delfosse, a member of the team from Grenoble University in France, said. "On the 'treasure map' of the Universe, one would be tempted to mark this planet with an X."

COROT, the first space telescope designed to search for Earth-like rocky planets around stars other than the Sun, was launched by the European Space Agency (ESA) last December. By 2020, at least one space telescope should be in orbit with the capability of detecting signs of life on planets light years from Earth.

MAELSTROM IN SPACE

THE Hubble Space Telescope has captured images of the tumultuous central region of the Carina Nebula where a maelstrom of star birth - and death - is taking place.

The image, one of the largest panoramas taken with Hubble's cameras, has been issued to mark the 17th anniversary of its launch.

The 50 light-year-wide view of the nebula shows star birth in a new level of detail. The landscape of the nebula is sculpted by outflowing winds and scorching ultraviolet radiation from the monster stars that inhabit this inferno.

In the process, the stars are shredding surrounding material that is the last vestige of the giant cloud from which they were born.

The nebula contains at least a dozen brilliant stars that are estimated to be at least 50 to 100 times the mass of our Sun.