Trillions of Rogue Planets Could Be Careening Through Our Galaxy

A new estimate suggests the Milky Way contains more free-floating planets than stars. It’s a big claim, but an upcoming mission might actually prove it. Rogue planets in our galaxy could number in the tens of billions and possibly even trillions, according to new research published in the Astronomical Journal. If confirmed, it means the Milky Way hosts more unbound, starless planets than it does stars. This estimate was developed in preparation for the Roman Galactic Exoplanet Survey (RGES), a five-year mission that’s scheduled to start in about five to six years. For the survey, NASA’s Nancy Grace Roman Space Telescope – scheduled to launch in 2025 – will...