How many other ‘Earths’ are out there?

New Zealand researchers are proposing a new method for identifying and recording Earth-like planets orbiting distant stars, anticipating there could be 100 billion such planets in the Milky Way alone.

Dr Phil Yock from the University of Auckland and colleagues are proposing to combine data from the NASA Kepler space telescope with a technique called gravitational microlensing to detect planets orbiting stars. Microlensing measures the bending of light that occurs as a star passes behind another object and distortions in this light can indicate the presence of an planet.

Previous microlensing research involving New Zealand astronomers has found that that, on average, every star in the Milky Way has at least one companion planet. Another study involving Dr Yock and the Japan/NZ collaboration MOA (Microlensing Observations in Astrophysics) also identified many ‘free floating’ planets, which do not orbit a star.

Dr Yock’s method, to be published this month in Monthly Notices of the Royal Astronomical Society, aims to provide an approximate figure for how many Earth-like planets there are in the galaxy.

“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,” Dr Yock said in a media release.

“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.”

Media coverage of the proposal includes:

Newstalk ZB: Aucklanders looking for aliens New Method To Find Earth-Like Planets Revealed
NZ Herald: A hundred billion reasons to keep looking for life
3 News: New technique to find Earth-like planets