Nature Astronomy, Published online: 15 June 2026; doi:10.1038/s41550-026-02841-6 By counting single atoms of 60Fe (which have a supernova origin), 244Pu and 247Cm (both formed via the r-process and independent of regular supernovae) in a deep-sea crust, the last actinide-producing r-process event near Earth is found to have occurred >100 Myr ago.