A Supernova Could Have Triggered the Mass Extinction of the Late Devonian Era

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A team of scientists hypothesizes that a supernova approximately 65 light-years away may have contributed to the mass extinction of the late Devonian Era, 359 million years ago. 

Killer cosmic rays from neighboring supernovae could be the culprit behind at least one mass extinction event. Scientists believe that finding specific radioactive isotopes in our planet’s rock record could confirm the scenario. Here is what you need to know. 

How Could A Supernova Trigger Our World?

New research led by the Urbana-Champaign astronomy and physics professor Brian Fields and the University of Illinois, investigates the possibility that astronomical events were the culprit for an extinction event 359 million years ago, between the Devonian and Carboniferous eras. 

The team of scientists focused on the Devonian-Carboniferous period because those rocks have hundreds of thousands of generations of plant spores that seem sunburnt by ultraviolet light (proof of a long-lasting ozone-depletion event). They also explored other astrophysical causes for ozone depletion, such as the solar eruptions, gamma-ray bursts, and meteorite impacts. But, they’re unlikely to cause long-lasting ozone-depletion. 

Fields explained: “We propose that one or more supernova explosions, about 65 light-years away from Earth, could have been responsible for the protracted loss of ozone.”

A supernova can produce a double strike, according to scientists. The blast immediately floods Earth with dangerous UV, gamma-rays, and X-rays. Then, the explosion of supernova debris hits the Solar System, subjecting the planet to prolonged irradiation from cosmic rays hastened by the supernova. The destruction to Earth and its ozone layer can last for up to 100,000 years. But how can scientists prove a supernova is the one to blame?

The team explained that they need to find the radioactive isotopes plutonium-244 and samarium-146 in the fossils and rocks accumulated at the time of extinction. Unfortunately, these isotopes don’t occur naturally on Earth nowadays. Their only way to get here is via cosmic explosions. 

The research continues as the team has yet to search for Pu-244 or Sm-146 in rocks from the Devonian-Carboniferous Era. 

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