Scientists at the University of Auckland believe they are one step closer to finding life in outer space.

The new theory estimates there are 100 billion planets like Earth in the Galaxy, and will use data from New Zealand's Mt John Observatory and Nasa's Kepler space telescope to find them.

The technique will find Earth-sized planets orbiting cool stars called red dwarfs. If they are far enough way from the stars they may be the right temperature to host life, said lead author physicist Dr Phil Yock.

"Kepler finds Earth-sized planets that are quite close to parent stars, and it estimates that there are 17 billion such planets in the Milky Way," he said.


"These planets are generally hotter than Earth, although some could be of a similar temperature - and therefore habitable - if they're orbiting a cool star called a red dwarf.

"Our proposal is to measure the number of Earth-mass planets orbiting stars at distances typically twice the Sun-Earth distance. Our planets will therefore be cooler than the Earth."

The Kepler data will combine with the observatory's data from a technique called gravitational microlensing - that detects the mass of a planet or star.

The microlensing is currently used by a Japan-New Zealand collaboration called Microlensing Observations in Astrophysics (MOA).

"By interpolating between the Kepler and MOA results, we should get a good estimate of the number of Earth-like, habitable planets in the Galaxy. We anticipate a number in the order of 100 billion.

"Of course, it will be a long way from measuring this number to actually finding inhabited planets, but it will be a step along the way."

A network of 12 telescopes in Chile, South Africa, Australia, Hawaii, Texas and the Canary Islands will also help to detect the planets.