If any of the planet-ending tropes of sci-fi come to pass in real life, we could now have a place to point our not-yet-real starships toward. NASA announced on Thursday that it has found the first near-Earth-size planet orbiting in the habitable zone of a star that is similar to our own sun.
Scientists don't yet know for sure if the planet spotted by the Kepler space telescope, dubbed Kepler-452b, can support life. It's in a region where temperatures are right for liquid water and is only about 60 percent larger than Earth, giving it a decent chance of being rocky like our own planet. NASA scientists also expect that Kepler-452b would have a slightly thicker atmosphere than Earth and probably still have active volcanoes, making it a pretty lively place even if it doesn't have life.
A year on the new planet is just 20 days longer than a year here and while its star is quite a long trek from home for humans at 1,400 light-years away in the constellation Cygnus, its sun is about the same size and temperature as our own. It's about 1.5 billion years older than our sun at 6 billion years, but it has nearly the same temperature and mass.
Kepler-452b, Earth's 'cousin,' in more detail (pictures)See all photos
The age of this distant solar system is also important because it provides plenty of time for life in a form similar to something like what we're familiar with to develop. In fact, Kepler-452b has had more than a billion-year head start on the Earth.
"In my mind this is indeed the closest thing we have to another planet like the Earth...to another place that someone else might call home," said Jon Jenkins, who leads Kepler data analysis at NASA. "Plants would photosynthesize just perfectly fine. It would feel a lot like home (in terms of) the sunshine you would experience."
There is one difference between Earth and Kepler-452b that distant future visitors would surely notice, however. The newly known planet has gravity nearly twice what we're used to, but Jenkins suspects that hypothetical human colonists would be able to withstand and adjust to being heavier.
"Astronauts find that gravity sucks after coming home (from a mission in microgravity)," added NASA's John Grunsfeld. "You feel really heavy, but your body responds to that."
Kepler has been hobbled by the failure of a couple of its four gyroscope-like reaction wheels a few years back and is no longer in top planet-hunting form, but scientists have continued to analyze the reams of data sent back and make new discoveries.
Kepler data has surfaced other near Earth-size planets in the habitable zone in the past. In fact, Thursday's announcement of Kepler-452b was also accompanied by news of 12 other new planet candidates near Earth size, and in orbit in their star's habitable zone. Of those, nine orbit stars are similar to our sun. These are just planet candidates that have yet to be confirmed like Kepler-452, which is the first confirmed planet spotted that hits the triumvirate of being the right size in the right place, and is also around a star that is the right size (at least from an Earth-centric perspective).
In recent years, the Kepler mission has helped paint a more complete picture of the universe, which it now seems clear is totally littered with planets. Among the hundreds and hundreds spied, there are others that appear comparable to Earth, and even to the far-off imaginary planets of the " universe.
The discovery of a planet potentially capable of supporting life is, of course, not the same as finding a planet harboring life. The next generation of ground-based and space telescopes will go a long way toward being able to identify the biosignatures -- things that often go along with life like oxygen, carbon dioxide or methane -- of a "breathing" planet when they begin to come online in the next few years.