Milky Way harbors trillions of wandering planets, study shows

A nine-year microlensing survey estimates roughly 21 planet-mass objects per star in the Milky Way, implying trillions of wandering planets that drift without a sun — most are low-mass and likely ejected from their birth systems. The result revises earlier claims of a Jupiter-mass excess and highlights a population dominated by small bodies. Future missions like NASA’s Roman Space Telescope and wide-field ground surveys will test and refine this census, but the measurement carries substantial uncertainty (roughly 8–44 per star) and depends on detecting brief microlensing events.