NASA's Kepler Finds the Most Earth-Like Exoplanet Ever Discovered
NASA's Kepler space telescope has just discovered three new Earth-like exoplanets, one of which is the closest analogue to Earth discovered thus far, and could potentially be an ideal host for alien life.
Yesterday, the Kepler mission announced that they found their 1,000th exoplanet, including three that are classified as "potentially habitable." All three planets are in the "Goldilocks zone" of their respective stars. This means that, like Earth, they are far enough away from their stars that liquid water wouldn't evaporate, but not so far that it would freeze. Furthermore, the planets are small, which makes it more likely that they have rocky surfaces, as larger worlds are usually composed of gas. Rocky surfaces and temperatures that allow for the presence of liquid water are the two most significant factors when judging a planet's habitability.
"With each new discovery of these small, possibly rocky worlds, our confidence strengthens in the determination of the true frequency of planets like Earth," said study co-author Doug Caldwell. "The day is on the horizon when we'll know how common temperate, rocky planets like Earth are."
One of these planets, dubbed Kepler 438b, has been deemed the most Earth-like planet ever discovered. It is an extremely small planet, only 12% larger than Earth, which means there's approximately a 70% chance that it is a rocky planet. It also lies in the habitable zone of its star, receiving 40% more light than Earth and completing an orbit every 35 days, making its years ten times shorter than Earth's. It tops the list of 24 potentially habitable planets found to date, beating out previous winners Kepler 186f, which is 10% larger than Earth and receives a third as much heat, and Kepler 62f, which is 40% larger and receives 41% as much heat.
"Kepler collected data for four years - long enough that we can now tease out the Earth-size candidates in one Earth-year orbits," said Fergal Mullally, a SETI Institute Kepler scientist. "We're closer than we've ever been to finding Earth twins around other sun-like stars. These are the planets we're looking for."