NASA held a news conference Feb. 22 at the agency’s headquarters to discuss the finding by the Spitzer Space Telescope of seven Earth-sized planets around a tiny, nearby, ultra-cool dwarf star.

Three of these planets are in the habitable zone, the region around the star in which liquid water is most likely to thrive on a rocky planet.

This is the first time so many planets have been found in a single star's habitable zone, and the first time so many Earth-sized planets have been found around the same star.

The finding of this planetary system, called TRAPPIST-1, is the best target yet for studying the atmospheres of potentially habitable, Earth-sized worlds.