Kepler, planet-hunting telescope that stirred up alien excitement, at center of NASA announcement this week

Two years after it stirred up speculation about the possibility of alien life, the Kepler Space Telescope will be at the center of a NASA announcement on Thursday.

NASA does not mention aliens explicitly in its description of the telescope's mission, but it does state that Kepler is on the hunt for planets like Earth.

"The challenge now is to find terrestrial planets (i.e., those one half to twice the size of the Earth), especially those in the habitable zone of their stars where liquid water might exist on the surface of the planet," NASA wrote.

In 2015, some Twitter users believed that Kepler had done more than that, trying to use aliens to explain its findings. Citizen scientists using the Planet Hunters program were studying dips in light of stars discovered by Kepler when they noticed peculiar dips from a star named KIC 8462852. Most dips in light could be explained by planets passing in front of the star, but these could not.

At the time, an associate professor of astronomy at Penn State University, Jason Wright, speculated that Kepler would have the ability to detect alien life, should it exist.

"The idea is that if advanced alien civilizations build planet-sized megastructures - solar panels, ring worlds, telescopes, beacons, whatever - Kepler might be able to distinguish them from planets," Wright wrote in a blog post.

The "internet went aflutter" using his theory in relationship to the strange discovery, Wright said, but he cautioned, "you should reserve the alien hypothesis as a last resort."

Later that year, NASA said the "unexplained and bizarre behavior" was likely a swarm of comets passing in front of the star.

As for this week's announcement, NASA mentioned that machine-learning from Google was used to make the discovery. Once again, though, aliens were not mentioned, so extraterrestrial enthusiasts will just have to wait and see.