Scientists have discovered the first Earth-sized alien planet in the habitable zone of its host star, which could have liquid water and the necessary conditions for life.
NASA confirmed the news during a press conference today, April 17.
The planet, called Kepler-186f, is approximately 490 light-years from earth, according to Space.com. Its host star is dimmer than Earth's sun, and it is slightly bigger than Earth in size, but not by much.
The positioning of the planet, when taking its size into consideration, could mean it has water on its surface, according to scientists.
"One of the things we've been looking for is maybe an Earth twin, which is an Earth-size planet in the habitable zone of a sunlike star," Tom Barclay, Kepler scientist and co-author of the new exoplanet research, said to Space.com. "This (Kepler-186f) is an Earth-size planet in the habitable zone of a cooler star. So, while it's not an Earth twin, it is perhaps an Earth cousin. It has similar characteristics, but a different parent."
Scientists believe that Kepler-186f orbits the Kepler-186 star at a distance of 32.5 million miles. In comparison, Earth orbits the sun from an average distance of 93 million miles, but the sun is larger than the Kepler-186 star.
While other planets have been found in the habitable zones of their stars, Kepler-186f is the first alien planet this close to Earth in size found orbiting a possible life-supporting location of an extrasolar system, according to scientists who spoke at the conference.
"This is the first definitive Earth-sized planet found in the habitable zone around another star," Elisa Quintana, of the SETI Institute and NASA's Ames Research Center and the lead author of a new study detailing the findings, said in a statement, according to Space.com.
The newly discovered planet is slightly larger than Earth, coming in at about 1.1 Earth radii, according to Space.com. Researchers have yet to figure out what the planet's atmosphere is made of, but once they do, it could help them figure out if the planet is hospitable to life or not.
"What we've learned, just over the past few years, is that there is a definite transition which occurs around about 1.5 Earth radii," Quintana said. "What happens there is that for radii between 1.5 and 2 Earth radii, the planet becomes massive enough that it starts to accumulate a very thick hydrogen and helium atmosphere, so it starts to resemble the gas giants of our solar system rather than anything else that we see as terrestrial."
Research was also published online today in the journal Science. The planet was discovered by scientists using the Kepler telescope.
The Kepler planet could be too dim for follow up studies however, which could prevent researchers from figuring out the planet's atmosphere.
NASA's James Webb Space Telescope, Hubble's successor, will launch sometime 2018. It is being designed to image planets around relatively nearby stars. The Kepler-186 system might be too far away for even the new powerful telescope to study, Barclay said.
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