Ancient Neutron-Star Merger Left a Rain of Radioactive Stardust on Earth

A deep-sea ferromanganese crust study found plutonium-244 and curium-247 patterns inconsistent with recent supernovae, pointing to an ancient r-process event—likely a kilonova from a neutron-star merger over 100 million years ago. The absence of curium-247, alongside iron-60 data, suggests the event predates more recent stellar explosions. Dust from this event has since dispersed through the galaxy, and Earth is still sampling remnants as it moves through space. This helps map the Milky Way’s explosive history and Earth’s heavy-element origins, though it’s unclear whether such ancient events affected life on our planet.