There should be billions of habitable, rocky planets around the faint red stars of our Milky Way galaxy, a new study suggests.

Though these alien planets are difficult to detect, and only a few have been discovered so far, they should be ubiquitous, scientists say. And some of them could be good candidates to host extraterrestrial life. The findings are based on a survey of 102 stars in a class called red dwarfs, which are fainter, cooler, less massive and longer-lived than the sun, and are thought to make up about 80 percent of the stars in our galaxy.