London: Astronomers have confirmed the discovery of an Earth-like planet which they say could be a potential future home for mankind outside the solar system.

The planet, Kepler 22-b, lies about 600 light-years away and is 2.4 times the size of Earth, and has a temperature of about 22C. It is the closest confirmed planet yet to one like ours -- an "Earth 2.0", says a team at NASA.

The new planet, confirmed by the astronomers using the US space agency's Kepler telescope, contains both land and water and has the right atmosphere to potentially support life, the media reported.

One of the key criteria for a planet to be habitable is that it remains roughly the right distance from its main star to be neither too cold nor too hot. And, the team says that the Kepler 22-b is in the "habitable zone" around a star not unlike our own.

However, the team does not yet know if Kepler 22-b, where a year lasts 290 days and first spotted two years ago, is made mostly of rock, gas or liquid.

"We have now got good planet confirmation with Kepler 22b. We are certain that it is in the habitable zone and if it has a surface it ought to have a nice temperature," Bill Borucki, Kepler space telescope's principal investigator at NASA Ames Research Centre, was quoted as saying.

There are now three planets outside the system, known as exoplanets, which experts believe could potentially be colonised by future generations.

In May, French astronomers identified Gliese 581d, pronounced "gleezer", which is far closer at around 20 light years away. It is about six times the mass of Earth and is one of a family of at least six planets.

In August, a team from Switzerland reported that another planet called HD 85512b and 36 light years away seemed to be habitable. The planet is in constellation of Vela, measures around 3.6 times the Earth's mass.

According to an online catalogue that indexes bodies outside our solar system by Planetary Habitability Laboratory of the University of Puerto Rico at Arecibo, a total of 47 exoplanets and exomoons are potential habitable candidates but not enough research has been done to be sure.