Is an exoplanet 1,200 lightyears away capable of sustaining life?

A distant planet 1,200 light years away from Earth, which may have rocky topography and an ocean, could be capable of sustaining life, according to a new study.

"We found there are multiple atmospheric compositions that allow it to be warm enough to have surface liquid water," lead author Aomawa Shields, a postdoctoral program fellow at the University of California, Los Angeles, said in a press release. "This makes it a strong candidate for a habitable planet."

Dr. Shields and a team from the University of Washington published their study about the planet Kepler-62f, first discovered during NASA's 2013 Kepler mission, in the journal Astrobiology. Scientists determined that Kepler-62f, which is about 40 percent larger than Earth, is the outermost of five planets that orbit a star smaller and cooler than the sun. The planet's size suggests it could be rocky and perhaps have oceans. 

The researchers used existing global climate models to simulate possible climates on Kepler-62f, while using the HNBody computer model to calculate its orbital path. They also entertained several possible scenarios of atmospheric conditions to determine whether the planet could sustain life.

With all this information, the team created computer simulations of the planet based on three different kinds of conditions. The first envisioned the planet with an atmosphere as thick as Earth or thicker. The second condition provided different carbon dioxide ranges, from about the same as Earth's to 2,500 times Earth's level. The third possible condition displayed different configurations for the planet's orbital path.

Kepler-62f could be habitable under several scenarios, they concluded, which differ by how much carbon dioxide is in the atmosphere. If its atmosphere were three to five times as thick as Earth's, for example, and composed completely of carbon dioxide, it might even sustain life year-round. But habitable conditions would be temporarily possible, during parts of its orbit, even if Kepler-62f only has the same amount of carbon dioxide as Earth. 

"If it doesn't have a mechanism to generate lots of carbon dioxide in its atmosphere to keep temperatures warm, and all it had was an Earth-like amount of carbon dioxide, certain orbital configurations could allow Kepler-62f's surface temperatures to temporarily get above freezing during a portion of its year," Shields said. "And this might help melt ice sheets formed at other times in the planet's orbit."

So far, over 2,300 exoplanets — planets that orbit stars outside the solar system — have been identified, but only a few dozen are potentially habitable. Yet even with these thousands of exoplanets, and a few thousand more planet candidates, it is still unconfirmed whether life exists outside Earth.

Shields said the same techniques used to study Kepler-62f could also be applied to other planets to determine whether or not they are habitable. "This will help us understand how likely certain planets are to be habitable over a wide range of factors, for which we don't yet have data from telescopes," said Shields. "And it will allow us to generate a prioritized list of targets to follow up on more closely with the next generation of telescopes that can look for the atmospheric fingerprints of life on another world."