Traces of a rare radioactive element believed to originate from a violent cosmic explosion have been discovered in oceanic deposits. Researchers examining deep-sea sediments have identified a unique isotope of plutonium, suggesting remnants of a kilonova—a powerful event triggered by the collision of neutron stars—may have reached Earth approximately 10 million years ago. Scientists are now directing their efforts towards lunar samples, anticipating that untouched moon soil could provide further proof of this phenomenon.
Deep-Sea Samples Reveal Clues of a Kilonova
As reported, according to a study presented at the 2025 American Physical Society Global Physics Summit, evidence of past supernovas has been uncovered through traces of radioactive isotopes in Earth’s ocean floor. Brian Fields, an astronomer at the University of Illinois Urbana-Champaign, has stated to Live Science that the accumulation of cosmic debris in Earth’s depths suggests the planet exists within a “supernova graveyard.” This finding aligns with previous studies where isotopic signatures linked to supernovas were detected, offering insight into the role these stellar explosions play in producing radioactive elements.
Rare Plutonium Isotope Suggests a Different Origin
In 2021, further analysis revealed the presence of a distinct plutonium isotope alongside previously identified radioactive iron. As per reports, the detection of this plutonium variant hinted at a more complex origin, leading scientists to suspect a kilonova event rather than just supernovas. Fields explained to Live Science that such collisions produce heavy elements, including gold and platinum, and suggested that mixing between supernova and kilonova remnants created a “radioactive cocktail” that ultimately settled on Earth.
Lunar Samples May Provide Definitive Proof
While Earth’s geological activity can obscure cosmic deposits over time, lunar soil remains largely undisturbed. Fields has noted that material deposited on the moon stays preserved, making it an ideal site for further investigation. Ongoing space missions, such as NASA’s Artemis program, are expected to return fresh lunar samples, which researchers hope to examine for additional evidence of past kilonova activity. Efforts are currently underway to advocate for the inclusion of these studies in upcoming lunar research initiatives.
