Rare plutonium isotope preserved in Pacific seabed points to an ancient cosmic explosion
Tiny traces of radioactive plutonium locked inside a slow-growing crust on the floor of the Pacific Ocean have helped scientists solve a cosmic mystery dating back more than 100 million years. In a study published on June 15, 2026, in Nature Astronomy, an international team reports that the last nearby event capable of forging many of the Universe’s heaviest elements occurred long before the supernovae whose signatures have already been found on Earth.










