WELLINGTON, July 4 -- New Zealand astronomers who took part in an international discovery of an Earth-sized planet with an Earth-like orbit around one of a set of twin stars say the find opens up the possibility of many more potentially life-hosting planets than previously thought.

Scientists from Auckland, Massey and Canterbury universities and Auckland's Stardome Observatory were among 64 authors named in an article on the discovery published in Science magazine Friday.

The planet was the first terrestrial planet with an Earth-like orbit ever discovered in a binary star system, a common constellation of two stars orbiting each other.

"This discovery is exciting because we weren't certain that terrestrial planets could form around one star of a binary star system," University of Auckland physics senior lecturer Nicholas Rattenbury said in a statement.

"This tells us there are many more stars in our galaxy that could potentially be the host star to habitable planets."

The new planet was 3,000 light years away and twice the mass of Earth. It orbited one of two stars in its binary system at about the same distance Earth orbits the Sun, but the star was much dimmer than the Sun, meaning the planet was extremely cold, at around minus 210 degrees centigrade, and unlikely to harbor life on its surface.

Astronomers found the planet by using technique known as microlensing, which measures how the gravity of a planet and its host star deflects light coming from background stars.

"Twenty years ago, the first extra-solar planet discoveries were being made. Today, we find it likely the galaxy is teeming with planets. Will some of them harbour life? That is of course the big question," said Rattenbury.