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According to researchers at the University of Illinois, a supernova 65 light years from Earth likely caused a mass extinction event during the Late Devonian period, 359 million years ago.
Researchers have found radioactive isotopes in rocks that may be able to confirm such an event, as detailed in a new article published in the journal Acts of the National Academy of Sciences.
During the Late Devonian Period, when most of life was in the oceans, one of the worst mass extinctions in Earth’s history severely damaged its ecosystem. Yet what caused it has never been clear.
To explain the event, the team examined rocks containing ancient plant spores. These spores appear to have been severely burned by ultraviolet light, possibly the result of a long-term lack of ozone in the atmosphere.
“Earth-based disasters such as large-scale volcanism and global warming can also destroy the ozone layer, but the evidence for these is inconclusive for the time interval in question,” said Professor D ‘Astronomy and Physics Brian Fields, senior author, in a statement. . “Instead, we propose that one or more supernova explosions, about 65 light years from Earth, could have been responsible for the prolonged loss of ozone.”
It would have been quite an event, lighting up the sky.
“To put this in perspective, one of the closest supernova threats today comes from the star Betelgeuse, which is over 600 light years away and well outside the 25-year destruction distance. light ”, graduate student and co-author of the study Adrienne Additiona Ertel.
The team also looked at other causes of ozone depletion, including meteorite impacts and gamma-ray bursts, but these would not have caused long-term depletion.
They suggest that the violent supernova flooded our planet with dangerous UV, X and gamma rays, irradiating the ozone layer with effects that would have lasted for up to 100,000 years, the researchers say.
To confirm their suspicions, the team is now looking for the “smoking gun” – two specific radioactive isotopes of plutonium, originating in the Late Devonian period, which could only have arrived on Earth from cosmic explosions.
“The overall message of our study is that life on Earth does not exist in isolation,” says Fields. “We are citizens of a larger cosmos, and the cosmos intervenes in our lives – often imperceptibly, but sometimes fiercely.
READ MORE: Star exploding 65 light years from Earth may have triggered mass extinction [Science Alert]
Learn more about supernovas: Scientists find bones are made of stars
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