New Earth-Like Planet Discovered

Because of its rocky nature and relatively good temperature, the scientists beleive the planet could be suitable for life.

"Astronomers have discovered the most earth-like planet outside our solar system to date," the European Southern Observatory (ESO) said in a statement on its website.

The planet, named Gliese 581 c, is five times the mass of the Earth and orbits a cool, dim "red dwarf" star located in the constellation of Libra, called Gliese 581.

It is 14 times closer to its star than the Earth to the Sun and completes a full orbit around its host star in 13 days.

This exoplanet, a term refers to planets around a star other than the Sun, is the smallest ever found till now.

The hosting star, smaller and colder than the Sun, is among the 100 closest stars to the Earth, located 20.5 light-years away.

It has a mass of only one third the mass of the Sun.

The discovery was made thanks to HARPS (High Accuracy Radial Velocity for Planetary Searcher), perhaps the most precise spectrograph in the world.

Located on the ESO 3.6-m telescope at La Silla, Chile, HARPS is able to measure velocities with a precision better than one meter per second (or 3.6 km/h).

Two years ago, the same ESO team found a Neptune-sized planet around Gliese 581, and their observations that time gave them a hint that a smaller planet, closer to Earth in size, might also encircle the star.

Not only did they find the Gliese 581 c, they also found indications of another planet, eight times the size of Earth, that completes an orbit in 84 days -- a discovery that makes Gliese 581 "quite a remarkable system," ESO said.

Life

The new planet lies in the habitable zone, the region around a star where water could be liquid.

Because of its rocky nature and relatively good temperature, members of the team who discovered the planet said it could be suitable for life.

"We have estimated that the mean temperature of this super-Earth lies between 0 and 40 degrees Celsius, and water would thus be liquid," explains Stéphane Udry, from the Geneva Observatory.

"Moreover, 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 fully covered with oceans."

Xavier Bonfils, a co-worker from Lisbon University, forecast a presence of water on the new planet.

"Red dwarfs are ideal targets for the search for low-mass planets where water could be liquid. Because such dwarfs emit less light, the habitable zone is much closer to them than it is around the Sun."

Xavier Delfosse, a member of the team from France's Grenoble University, predicted the planet would a target for future space missions.

"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," he said.

"On the treasure map of the Universe, one would be tempted to mark this planet with an X."

Even though Gliese 581 offers such promise, it would be impossible for mankind to reach it, or even send an unmanned scout probe, using current technology.

Chemical rockets generate only a fraction of the light speed needed to get there within a human timescale.