‘Alien Earths’ are more common than previously thought

When astronomers search the stars for exoplanets, the most exciting discoveries have to be those that could possibly support life. Now, a new study out of Penn State University says that these potentially life-bearing planets are more common than we think, and there may be some orbiting around nearby stars.

This study, conducted by Ravi Kopparapu, a post-doc researcher in Penn State's Astrobiology Group, focused on smaller, cooler stars, called 'red dwarfs'. Planets tend to orbit much closer around these stars than they do around larger, brighter stars, and coincidentally, the habitable zone of these red dwarfs — the region where liquid water can exist on the planet's surface — is also closer in. This means that more of the planets around these stars are likely to be inside their habitable zone.

[ Related: Extraterrestrial Life May be Common Around Binary Stars ]

"We now estimate that if we were to look at 10 of the nearest small stars we would find about four potentially habitable planets, give or take," said Kopparapu. "That is a conservative estimate. There could be more."

This study not only predicts more habitable worlds, but it also predicts that we will find these planets closer to us than previously thought.

"The average distance to the nearest potentially habitable planet is about seven light years. That is about half the distance of previous estimates," Kopparapu said. "There are about eight cool stars within 10 light-years, so conservatively, we should expect to find about three Earth-size planets in the habitable zones."

[ More Geekquinox: Curiosity finds conditions suitable for past life on Mars ]

Kopparapu's work builds on a recent study by the Harvard-Smithsonian Center for Astrophysics, that sought to estimate the number of Earth-sized planets orbiting in the habitable zones of nearly 4,000 red dwarf stars. Their study used the older, 1993 definition for a star's habitable zone, but this new study uses more recent updates to that definition, which widen the range of orbits where a planet could possibly harbour life.

"I used our new habitable zone calculations and found that there are nearly three times as many Earth-sized planets in the habitable zones around these low-mass stars as in previous estimates," said Kopparapu. "This means Earth-sized planets are more common than we thought, and that is a good sign for detecting extraterrestrial life."

Geek out with the latest in science and weather.
Follow @ygeekquinox on Twitter!

Our goal is to create a safe and engaging place for users to connect over interests and passions. In order to improve our community experience, we are temporarily suspending article commenting