A supernova nearby may have triggered a mass extinction 2.6 million years ago

Cosmic rays from a supernova may have wiped out the Megalodon!

Key Takeaways

1. A nearby supernova 2.6 million years ago might have triggered a mass extinction.
2. Radiation from cosmic rays likely increased cancer rates in marine megafauna, including the Megalodon.
3. Evidence includes a spike in radioactive iron-60 linked to the supernova.
4. The Local Bubble, created by supernovae, could have amplified radiation exposure.
5. This study offers a new explanation for the mysterious marine extinction at the Pliocene-Pleistocene boundary.

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Cosmic Radiation: A Supernova’s Deadly Reach

Around 2.6 million years ago, a supernova erupted just 150 light-years from Earth, creating a dazzling display in the sky. But its most significant impact may have occurred years later when a wave of cosmic radiation reached Earth, triggering a marine extinction event. Researchers led by Adrian Melott of the University of Kansas propose that this cosmic catastrophe may have contributed to the disappearance of marine giants, including the Megalodon. Their findings were published in Astrobiology.

Radiation from the supernova bombarded Earth’s atmosphere, producing high-energy cosmic rays composed of muons. These particles, hundreds of times heavier than electrons, penetrated deep into Earth’s waters. The team’s calculations suggest that muon exposure could have increased cancer rates in large animals by 50%, with even more pronounced effects on massive creatures like whales. Coastal waters, being shallower, bore the brunt of this radiation, coinciding with a significant extinction event that wiped out 36% of marine genera.

Evidence Written in the Stars and Rocks

A key piece of evidence linking the supernova to the extinction is the presence of iron-60, a radioactive isotope with a half-life of 2.6 million years. Found in geological layers from that era, iron-60 could only have arrived on Earth via cosmic sources like supernovae. This radioactive signature provides a timeline that aligns perfectly with the Pliocene-Pleistocene extinction.

Further, the Sun’s location within the Local Bubble—a 300-light-year-wide region of hot, sparse gas created by ancient supernovae—may have amplified the effects of this radiation. The bubble’s boundaries could have reflected cosmic rays back toward Earth, creating a prolonged exposure lasting tens of thousands of years.

New Light on Extinction Mysteries

This chain of events offers a compelling explanation for the unexplained marine extinction, suggesting that cosmic forces played a direct role in shaping life on Earth. By combining astrophysical data and geological evidence, the study highlights the profound influence of distant cosmic events on Earth’s history. As Melott concludes, “This could be the first direct connection between a supernova and a major extinction event.”