Moon-Mass Primordial Black Hole Hinted by Stellar Microlensing Event

Astronomers analyzing a 2019 microlensing flare of a star in the Large Magellanic Cloud say the signal is best explained by a moon-mass primordial black hole—Phoebe—likely in the Milky Way's dark matter halo about 60,000 light-years away. While a rogue exoplanet could cause similar lensing, the PBH explanation is favored and, if confirmed, would illuminate dark matter and early-universe physics and spur high-cadence microlensing surveys with the Roman and Vera Rubin observatories. Some related analyses (e.g., Andromeda PBH candidates) have contested the PBH interpretation, so confirmation will require more sensitive observations.