Is it another Earth?
The latest exoplanet discovery has astronomers pondering the possibility that it could be an exact replica of our own planet Earth, and that it could possess the ability to host life.
The discovery was announced at the meeting Monday by Christopher Burke of the SETI Institute as part of a batch of 461 new planet candidates discovered by Kepler. The object, which has a radius 1.5 times that of Earth and has been dubbed KOI 172.02, is the smallest planet ever discovered outside our solar system. Astronomers involved in the latest study say is is likely a rocky planet, raising the prospect that it may have the ability to hold life. According to NASA, the planet takes 242 days to orbit its star (similar to Earth’s 365 days) and is about three-quarters of the Earth-sun distance from its parent star.
“This was very exciting because it’s our first habitable-zone super-Earth around a sun-type star,” astronomer Natalie Batalha, a Kepler co-investigator at NASA’s Ames Research Center in Moffett Field, California, said in a statement released Tuesday.
The system in which the planet resides has captured the attention of the astronomy community. The object’s host star is a G-type star, making it slightly cooler than our own sun, a finding that is in and of itself significant. Astronomers have — until now — been unable to detect planets orbiting stars similar in size to our own sun.
“It’s orbiting a star that’s very much like our sun,” Batalha noted. “Previously the ones we saw were orbiting other types of stars.”
The finding is seen as a major success for NASA’s Kepler Space Telescope. The project, which has captured national attention over the course of the past several months, has already captured images of thousands of possible planets, and astronomers around the world have spent the past months sorting through the data in an effort to better identify the objects.
According to NASA, the latest planetary finding is especially interesting. It remains unclear whether the latest planet lies within the so-called “habitable zone,” the region in the planetary system where liquid water might exist on the surface of a planet. NASA astronomers said it will take a number of additional transit events — when the planet passes in front of its star — in order to fully confirm the planet’s position, although early data suggest it resides within the zone.
NASA’s Kepler mission, which was recently extended an additional three years, has drawn on the skills of astronomers around the world. The latest discovery is seen as another example of a continuing trend of discovering smaller Earth-like planets. Based on observations conducted from May 2009 to March 2011, astronomers have steadily increased their ability to identify the number of smaller-size planet candidates and the number of stars with more than one candidate. Since the last Kepler catalog was released in February 2012, the number of candidates discovered in the Kepler data has increased by 20 percent and now totals 2,740 potential planets orbiting 2,036 stars, according to the U.S. space agency.
The announcement follows in the wake of a string of findings for NASA’s Kepler. Earlier this week, NASA’s Kepler mission announced the discovery of 461 new planet candidates. Four of the potential new planets are less than twice the size of Earth and orbit in their sun’s “habitable zone.” Meanwhile, the Planet Hunters citizen science project, which is not associated with NASA, announced its second confirmed world—PH2 b, a Jupiter-sized planet orbiting in its star’s habitable zone—as well as 42 planet candidates, 15 of them in their stars’ habitable zones.
With astronomers racking up the number of Earth-like planets, astronomers have openly pondered whether it is simply a matter of time before an Earth-like planet that actually hosts life is discovered. Speaking at the American Astronomical Society (AAS), Batalha said NASA’s Kepler team will continue its attempts to discover planets, noting that its end goal is to discover life beyond our own planet.
“That is certainly the big picture goal, that is what NASA is aiming to do, to find the next Earth and ultimately to find other life in the galaxy,” Batalha said.
The new planet discovery was announced Monday January 10 during the ‘Exoplanets & Their Host Stars’ presentation at the AAS conference in Seattle, Washington.