Billions of orphan planets identified in the Milky Way

Astronomers have estimated that the Milky Way may contain billions of rogue planets—worlds that drift through space without orbiting a star. Recent observations and improved instruments have allowed scientists to move beyond the hypothesis that such planets are rare, confirming their abundance across the galaxy.

The study attributes the prevalence of these orphan planets to two main processes. First, dynamic ejection in young planetary systems can catapult lighter planets out of orbit when massive bodies interact gravitationally, effectively ejecting them into interstellar space. Second, some planets may form in isolation, never having been bound to a star. Both mechanisms explain how numerous worlds can exist in perpetual darkness, cold and untethered to any solar radiation.