Scientists using NASA’s Kepler spacecraft are getting tantalizingly close to their goal of locating extra-terrestrial life.
On Tuesday, the agency announced the discovery of the first Earth-sized exoplanets (planets outside our solar system).
Kepler-20e and Kepler-20f are both approximately the size of Earth and orbit a Sun-sized star located 1,000 light years away from Earth in the constellation Lyra. Both are thought to have rocky surfaces.
“This discovery demonstrates for the first time that Earth-size planets exist around other stars, and that we are able to detect them,” said Francois Fressin of the Harvard-Smithsonian Center for Astrophysics, a Kepler scientist and the lead author of a paper on the finding published in the journal Nature.
Unfortunately, neither planet is a likely candidate for life as both planets are located outside of their star’s “habitable zone,” the space where surface temperatures and conditions would be suitable to support liquid water, thought to be a necessary precondition for life. Both planets are too close to their star, and thus too hot, to have liquid water on their surfaces.
Still, the discovery marks an important leap forward in NASA’s search for planets capable of supporting extra-terrestrial life, and the crowning achievement on a year filled with amazing discoveries, perhaps the most exciting of which came just earlier this month, when NASA announced that Kepler’s sky-survey had pinpointed a planet in the habitable zone around its star.
Kepler-20f, the fourth planet from the star in the Kepler-20 system, has an extremely short year, orbiting its star every 19.6 days. Being that close, its surface temperature is a scorching 800 degrees. It is 3 percent larger than Earth, according to a measure of its radius. Here’s an artist’s rendering of the planet:
Still, one Kepler scientist, Linda Elkins-Tanton of MIT, speculated in a NASA press conference announcing the discovery Tuesday that Kepler-20f might have had liquid water and been inhabited billions of years ago, before the planet moved closer to its star.
Kepler-20e, the third planet, is actually even hotter, with a surface temperature of 1400 degrees and a shorter orbital period, leading to a 6-day-long year. It is a bit smaller than Earth, about 87 percent Earth’s size, according to NASA. Here’s the artist’s rendering of it:
The other three planets in the Kepler system — gas giants — are also located close to the system’s star, all falling within a distance equivalent to Mercury’s orbit in our solar system — leading NASA scientists to believe that they formed much further out from a “disk of material” that has since pushed them inward.
NASA’s Kepler unmanned spacecraft orbits the Sun with its telescope (a light-sensing photometer) pointed in a star-dense area of the sky between the constellations Cygnus and Lyra.
Kepler also relies on observations from ground-based telescopes to double-check its findings, but the area of its focus is on visible from the ground in the northern hemisphere during the summer.
The Kepler mission, which began in 2009, is approaching the end of its allotted three-year lifetime, but scientists are hoping to extend it, along with their search for extraterrestrial life, up to 7 years.
Watch the following video from NASA for an overview of the Kepler system and the new discoveries:
We’ve reached out to the Kepler team for more information on the discoveries and will update when we receive a response.
