Astronomers have confirmed the existence of an earth-like planet in the "habitable zone" around a star similar to our own sun.

The planet, Kepler 22-b, is 600 light-years away from earth, measures 2.4 times the size of earth, and has a temperature of about 22 degrees C.

According to experts, the planet is the closest confirmed planet yet to one like ours – an ''Earth 2.0.''

However, the team has not yet been able to determine the composition of Kepler 22-b whether it is made up of rock, gas or liquid.

During the conference at which the result was announced, the Kepler team also said that it had identified 1,094 new candidate planets. This nearly doubles the number of potential far-flung worlds, the telescope had uncovered so far.

Kepler 22-b was among 54 exoplanet candidates in habitable zones reported by the Kepler team in February. It is only the first to be formally confirmed using other telescopes.

More such ''Earth 2.0" candidates are expected to be confirmed in the near future. However, due to a redefinition of the habitable zone's boundaries, the number of potential candidates is down to 48. Among these 10 are of the size of the earth.

The Kepler space telescope was designed to look at a fixed slice of the night sky, with intensive focus on around 150,000 stars. The telescope is highly sensitive in detecting light variations and can accurately pick up the motion of planet as it transits across its host star, which dims the star's light by a miniscule amount.

Kepler 22-b lies 15 per cent closer to its sun than the distance of the earth from the sun, and its year lasts around 290 days. However, the planet's host star puts out about 25 per cent less light, which keeps the planet at a temperature that could support the presence of liquid water.

It is the first planet NASA's Kepler mission has confirmed to be orbiting in the habitable zone of a star - the region around a star where liquid water, a requirement for life, could be present.
 
According to Bill Borucki, Kepler principal investigator at NASA Ames Research Center, NASA was certain that it was in the habitable zone and if had a surface, it would probably have a nice temperature.

Kepler is NASA's first mission looking for earth-like planets orbiting suns not unlike ours.

It carries the largest camera ever sent into space - a 95-Mp array of charge-coupled devices. The mission is expected to continue sending information back to earth until at least November 2012.

Kepler is on the look out for planets the size of the earth, including those orbiting stars in a warm, habitable zone which could support the presence of liquid water on the surface of the planet.

With the latest addition to the count of ''Earth 2.0'' candidates, the total number confirmed by global astronomers has increased to three.

Read more: First habitable super-Earth discovered in orbit around a Sun-like star