Little red dwarfs have become a big focal point for astronomers hunting for habitable planets. For a long time, planet-hunters focused on bigger stars similar to our own sun. After all, we only know of one place where life successfully evolved—so it makes sense to try to find solar systems as close to our own as possible. That's why "Earth-like" exoplanets get so much buzz, too: these are worlds that researchers estimate to be rocky, based on their mass and their distance from their host star (as opposed to massive planets made of gas), so they have surfaces not totally unlike the own found on our own planet. In theory, rocky worlds that sit in their star's "habitable zone"—not so close as to turn into a sizzling rocky like Mercury, but not so distant as to freeze over like Pluto—could maintain liquid water, given the proper atmosphere. And we know water is a key ingredient for life, at least as we know it.