Kepler 438b: 'Alien Earth' among 8 new planets discovered by NASA space telescope
The planet - called Kepler 438b - sits within the 'habitable zone' of its host star and is only a little warmer than Earth
One of eight new planets discovered a super-powerful NASA telescope is the most Earth-like yet discovered.
It is one of two of the eight which have significant similarities to our own planet.
All of the group could possess watery oceans and life.
The new worlds double the number of small exo-planets believed to be circling their stars in the "habitable zone" - the narrow region in which temperatures are mild enough to allow liquid surface water.
By "small" astronomers mean planets with less than twice the Earth's diameter.
"Most of these planets have a good chance of being rocky, like Earth," said lead scientist Dr Guillermo Torres, from the Harvard-Smithsonian Centre for Astrophysics in Cambridge, US.
All eight were picked out by Nasa's Kepler space telescope.
The super-powerful device has now found more than 1,000 exo-planets.
The planet most like Earth in the new group sits within the 'habitable zone' of its host star and is only a little warmer than this planet.
The find was revealed at a meeting of the American Astronomical Society, the BBC reports.
The planet which is most Earth-like has been named Kepler 438b.
Researchers believe it is likely to be even more similar to our planet than Kepler 186f - which previously held the title of most Earth-like planet.
Kepler 438b is 12% larger than Earth.