It's no secret that there are planets outside of our solar system that are possibly habitable and capable of sustaining life. Now, astronomers have discovered two more such planets, those that exist within their star's habitable zones.
These two newly discovered planets, Kepler 483-b and Kepler 442-b, are also both about the same size and mass as Earth, which makes it even more likely that they contain some form of life on their surfaces.
Because of their existence in their star's habitable zones, both planets are also probably rocky, like Earth, and get about the same amount of heat from their star as Earth gets from the sun.
Perhaps an even more interesting thing about these two planets is that they are the closest potentially habitable exoplanets to Earth we've found to date. Of course, the word "close" is relative when referring to cosmic distances, especially when these planets are still 500 and 1,100 light-years away. With a light year being nearly 6 million miles, that's still quite a distance.
Kepler 438-b is only about 12 percent bigger than Earth, but it gets 40 percent more heat from its sun. This means that its temperatures are warm, up to 140 degrees, but as there are some bacteria on Earth that can survive such extreme temperatures, astronomers aren't ruling it out as potentially habitable.
Kepler 442-b is larger, about 34 percent bigger than Earth. It gets less energy from its sun, but because of its location in the habitable zone and its size, astronomers still consider it as potentially habitable, too.
Of course, we have no proof that life exists on these planets, and that sort of evidence is years away.
"These planets do exist; we didn't know that before," says astronomer Guillermo Torres from the Harvard-Smithsonian Center for Astrophysics.. "What we're really looking for is signs of life eventually. We're not there yet. It will take many years but this is the first step."
NASA's Kepler spacecraft recently confirmed its 1,000th planet, which is quite an achievement, especially considering that Kepler lost functionality after its positioning wheels failed last year. However, thanks to some clever NASA thinking, Kepler is back up and running and its mission continues.
"Each result from the planet-hunting Kepler mission's treasure trove of data takes us another step closer to answering the question of whether we are alone in the Universe," says John Grunsfeld, associate administrator of NASA's Science Mission Directorate. "The Kepler team and its science community continue to produce impressive results with the data from this venerable explorer."
[Photo Credit: D. Aguilar/Harvard-Smithsonian Center for Astrophysics]
