Washington: A new study estimates that there may be twice the number of habitable planets than previously thought - thanks to new calculations that include the effect of clouds on alien worlds.
The finding suggests that the Milky Way alone may host 60 billion such planets around faint red dwarf stars.
Researchers at the University of Chicago and Northwestern University based their study on rigorous computer simulations of cloud behaviour on alien planets.
This cloud behaviour dramatically expanded the habitable zone of red dwarfs, which are much smaller and fainter than stars like the Sun.
Current data from NASA`s Kepler mission, a space observatory searching for Earth-like planets orbiting other stars, suggest there is approximately one Earth-size planet in the habitable zone of each red dwarf. The Chicago-Northwestern study now doubles that number.
"Most of the planets in the Milky Way orbit red dwarfs," Nicolas Cowan, a postdoctoral fellow at Northwestern`s Center for Interdisciplinary Exploration and Research in Astrophysics, said.
"A thermostat that makes such planets more clement means we don`t have to look as far to find a habitable planet," he said.
The findings are published in the journal Astrophysical Journal Letters.