Our Milky Way galaxy is home to at least 100 billion alien planets, and possibly many more, a new study suggests.

“It’s a staggering number, if you think about it,” lead author Jonathan Swift, of Caltech in Pasadena, said in a statement. “Basically there’s one of these planets per star.” Swift and his colleagues arrived at their estimate after studying a five-planet system called Kepler-32, which lies about 915 light-years from Earth. The five worlds were detected by NASA’s Kepler Space Telescope, which flags the tiny brightness dips caused when exoplanets cross their star’s face from the instrument’s perspective.