Milky Way: Home to 100B+ Planets

Scientists have done a sort of "cosmic census," completing a new study that finds the Milky Way galaxy is home to 100 billion alien planets—and maybe even many more than that. "It's a staggering number, if you think about it," says the lead author. "Basically there's one of these planets per star." The researchers figured the estimate by studying Kepler-32, a five-planet system that, they say, is representative of many such systems in the galaxy, Space.com reports.

The planets orbit around the most common type of star in the galaxy, and they are similar in size and orbit pattern to other planets spotted orbiting around the same type of star. "This is as close to a Rosetta stone as anything I've seen," says a co-author. "It's like unlocking a language that we're trying to understand—the language of planet formation." Scientists only estimated the number of similar planet systems, meaning that their estimate is probably rather conservative; the lead author estimates there could actually be 200 billion planets in the galaxy. (More planets stories.)