A team of astronomers, including New Zealand scientists, has concluded that most of our galaxy's estimated 100 billion stars have at least one planet.
The study published in the scientific journal Nature suggests each star has on average 1.6 planets orbiting it.
An astronomer who took part in the study, Dr Michael Albrow from the University of Canterbury, says about 1000 planets have so far been spotted outside our solar system.
Some of the stars were located using gravitational microlensing, a technique that measures the bending of light as a star passes behind another object. Distortions in this light can indicate the presence of an planet.
Dr Albrow says only a small fraction of planets orbit in a zone where water could exist but because of the sheer size of the Milky Way that still leaves about 10 billion planets which could support life.
He says astronomers are shifting their focus from discovering new planets to learning more about what conditions are like on other worlds.