Santa Cruz, California – In a twist reminiscent of a cosmic detective story, scientists at the University of California Santa Cruz have linked mysterious radioactive materials found on Earth’s seafloor to ancient stellar explosions, sparking new insights into not only celestial phenomena but also potentially revolutionary biological changes here on Earth. The primary clue in this interstellar investigation is iron-60, a radioactive isotope absent in Earth’s formation and pointing to an extraterrestrial origin attributed to supernovae activity.
The UC Santa Cruz team meticulously analyzed the isotope’s age and distribution, discovering notable concentrations that originated from two distinct time periods approximately 2.5 million and 6.5 million years ago. This timeline aligns with the period when Earth ventured into the Local Bubble, a vast cavity in space created by consecutive supernova blasts that likely occurred between 10 to 20 million years ago.
As Earth passed through the dense, radiation-rich boundary of this bubble roughly 6 million years ago, it presumably encountered the remnants of these explosions, capturing the iron-60 isotopes in its ocean beds. The more recent and significant accumulation of this isotope, however, seems tied to a direct supernova event. The researchers identified potential origins by tracing the movement of nearby stars and clusters, pinpointing two possible sources: the Tucana-Horologium or Upper Centaurus Lupus clusters, located 228 and 457 light-years away, respectively.
Simulations suggest that the explosion responsible could have showered Earth with high-energy cosmic rays for around 100,000 years, sufficiently long to embed the iron-60 into the sediment and possibly influence biological evolution. High levels of radiation have the potential to cause DNA mutations—introducing both harmful effects like increased cancer rates and beneficial evolutionary adaptations.
Such DNA mutations may serve as catalysts for significant evolutionary shifts. Highlighting this, Caitlyn Nojiri, the lead author of the study, noted earlier research connecting a similar cosmic event to the extinction of large marine animals like the Megalodon, a prehistoric shark, suggesting that the radiation could have altered life trajectories on Earth dramatically.
Furthering this line of inquiry, the researchers found a curious correlation with major biological developments on Earth coinciding with these cosmic events. For instance, notable diversification of viruses in Lake Tanganyika in Eastern Africa occurred between two and three million years ago, a period overlapping with one of the increased iron-60 deposits.
Although direct connections between these terrestrial changes and cosmic events are still speculative, the synchronous timing suggests a potentially transformative impact of extraterrestrial phenomena on Earth’s biological evolution. This hypothesis opens new avenues for research, not only in understanding life’s history on Earth but also potentially aiding the search for life on other planets by examining the effects of similar cosmic events.
The findings, published in The Astrophysical Journal Letters, paint a picture of a universe in which celestial events reach down into the fabric of Earth’s biological life, suggesting that the history of life on our planet may be far more intertwined with the stars than previously understood. This revelation beckons further exploration into how cosmic rays and supernovae might influence life not only here but also on distant worlds, potentially guiding future astrobiological exploration.