Although the “we are not alone” crowd received some bad news yesterday when it was reported that KIC 8462852 (a.k.a. Tabby’s Star) most likely does not have alien megastructures orbiting around it, hope for finding life on other planets — or at the very least planets that could potentially support life — is not lost.
NASA has announced that Kepler, the spacecraft that orbits Earth scanning a small slice of the cosmos for planets, has just doubled the number of exoplanets it’s found, bringing the total number of verified candidates to nearly 3,200.
NASA reports that in Kepler’s “July 2015 planet candidate catalog,” 4,302 possible exoplanets (exoplanets are planets that orbit around other stars than our own) were found, 1,284 of which have a possibility of 99% or greater of being a planet. 1,327 of those candidates are also probably planets, but do not meet NASA’s 99% requirement to be labeled as such.
Kepler, a spacecraft that was launched into orbit around Earth in 2009, is able to identify exoplanets by tracking how much light it receives from a given star. While the light a given star emits remains roughly constant, if something passes between the star and Kepler, there will be a dip in how much light Kepler receives. This means that if Kepler senses a periodic dip in light coming from a star, there’s a good chance that’s because an orbiting planet passed between it and the star. This method for detecting exoplanets is shown in the transit graph in the above video.
Paul Hertz, Astrophysics Division director at NASA Headquarters said of Kepler’s most recent findings that “Before the Kepler space telescope launched, we did not know whether exoplanets were rare or common in the galaxy. Thanks to Kepler and the research community, we now know there could be more planets than stars.” The number of stars in our Milky Way galaxy, for reference, has been estimated at anywhere from 100 billion to 400 billion.
Perhaps the most exciting highlight of Kepler’s “newly-validated batch of planets” is that 550 are rocky planets like Earth (based on size), nine of which are in the “habitable zone” — the orbital band around a star where it’s not too hot, not too cold, but juuuuust right to support liquid water. (There is now a total of 21 habitable-zone planets that have been discovered.)
Many more exoplanets are likely to be discovered in the near future as well, because NASA is launching TESS, the Transiting Exoplanet Survey Satellite, in 2018, which will scan an additional 200,000 stars for planets on top of the 150,000 stars that Kepler already scans. Megastructures or no megastructures, the odds that we are indeed not alone is now increasing faster than ever.
Do you think we’re alone, or is there most definitely more life out there in the cosmos? Let us know your thoughts in the comments below!
Images: NASA/W. Stenzel; Princeton University/T. Morton; NASA Ames/W. Stenzel