A few years ago it looked like NASA’s Kepler space telescope was a complete loss. After two of its four reaction wheels failed, Kepler was no longer able to keep itself pointed at distant stars while searching for exoplanets. NASA figured out an ingenious workaround for the problem and resumed limited planet hunting in 2014. Now the first big cache of results from the revived Kepler are in, and they include what may be the most Earth-like exoplanet yet.
Kepler was designed and deployed with the singular purpose to watch the heavens for signs of exoplanets orbiting distant stars. It does this by analyzing the light output from a large number of stars over time. When the light dips in a certain way, that points to the presence of a planet in orbit that just happened to pass between its star and Kepler. This so-called transit method for detecting exoplanets is the most effective one we have, but it only works when the plane of an alien solar system is aligned just right.
The fix for kepler means it can only search for exoplanets at a few places in its orbit, but the new data still contains eight previously undiscovered exoplanets. Most of these are gas giants, outside the habitable zone, or both. One of them, however, is only 12% larger than Earth and sits in its star’s habitable zone where liquid water could exist. The planet, currently known as Kepler 438b, orbits a small and cool red dwarf star, but it’s much closer than Earth is to the sun. Astronomers estimate it sees as much as 40% more heat from it sun than Earth. The sky would also be red on Kepler 438b, not that we’ll get to see it any time soon.
This solar system is 475 light years away, which is nothing in astronomical terms. That’s an insurmountable distance when you’re a resident of Earth without access to any magical, futuristic faster-than-light travel. Even if we could get there, Kepler can’t tell us what the planet is really like. We know that it’s only 12% larger than Earth, but for all we know it could be extremely dense, and thus have too much gravity to be considered habitable by our standards. Although “habitable” is a loose term anyway.
In addition to Kepler 438b, there are two other planets in the new data that could be considered Earth-like. They’re larger and probably have more extreme temperatures, but they bring to eight the total number of habitable-zone exoplanets. Kepler has spotted over 1000 total exoplanets and will continue to operate at least through next year.
NASA hopes Kepler can keep spotting exoplanets in some limited capacity at least until the James Webb Space Telescope is launched in 2018. When it’s deployed, Webb will use infrared analysis to study a variety of objects that are too cool to be seen by other telescopes. This includes exoplanets, but also brown dwarfs, comets, and Kuiper Belt objects like Pluto.Credits:Geek.com
