Washington: Earth-like rocky planets that humans could live on may be more common in the universe than stars, says an international team of planetary scientists which included an Indian-origin researcher.
Aditya Chopra at Australian National University and colleagues claim that determining whether these planets are habitable has become the new holy grail of astronomy.
"The new-found abundance of planets, combined with the much larger range of inhabited terrestrial environments suggests that habitable planets are common. This increases the probability of finding some kind of extraterrestrial life," said Charley Lineweaver, who led the team.
Chopra said the best estimates of habitability come from the planet we know best -- Earth.
"By comparing the inhabited and uninhabited regions of Earth, we can identify the most important factors that determine habitability. For terrestrial life, those factors are liquid water, a narrow range of temperature, and an energy source," he said in a university release.
Dr Lineweaver added: "Habitability is not just a question of abiotic environmental conditions -- the presence of life may be required to maintain the habitability of a planet over billions of years.
"Planetary habitability is a complex and confusing concept that we are only beginning to get our heads around, but as a species that wants to survive, it is in our interest to get our heads around it soon."
The findings have been published in the `Annual Reviews of Earth and Planetary Sciences` journal.