Astronomers this week published a new study that estimates six percent of red dwarf stars may have Earth-sized planets orbiting within their "habitable zone" - the area around a star in which liquid water can exist on the surface of an orbiting body. Since many stars close to our solar system are red dwarfs, astronomers say an Earth-like planet could be just 13 light-years away.
"We thought we would have to search vast distances to find an Earth-like planet.," said Courtney Dressing, lead author of the paper and an astronomer at Harvard University. "Now we realize another Earth is probably in our own backyard, waiting to be spotted."
The research, to be published published in The Astrophysical Journal, came from data from NASA's Kepler space telescope. 95 planet candidates orbiting 64 red dwarf stars were analyzed, and three of them were found to be smaller than twice the size of earth and orbiting in their stars' habitable zone.
"We don't know if life could exist on a planet orbiting a red dwarf, but the findings pique my curiosity and leave me wondering if the cosmic cradles of life are more diverse than we humans have imagined," said Natalie Batalha, Kepler mission scientist at NASA's Ames Research Center.
Though the planets may be similar to Earth in some ways, the nature of a red dwarf system could mean they are very different in others. Since the habitable zone of a red dwarf is closer to those stars than our own, planets within that zone would be more susceptible to solar flares. Also, such planets would likely be very old and tidally locked to their star, leaving one side of the planet in perpetual darkness. Astronomers suggest, however, that a thick atmosphere could counteract these effects, and that such stresses could even help life evolve.
"You don't need an Earth clone to have life," said Dressing.
(Image courtesy D. Aguilar/Harvard-Smithsonian Center for Astrophysics)