According to researchers from the University of Illinois, a supernova 65 light-years from Earth probably caused a mass extinction event in the Late Devonian period, 359 million years ago.
The researchers found radioactive isotopes in rocks that could possibly confirm such an event, as detailed in a new paper published in the journal Procedures of the National Academy of Sciences.
During the Late Devonian period, when most life was found in the oceans, one of the worst mass extinctions in the history of the earth severely damaged its ecosystem. Yet it has never become clear what caused it.
To explain the incident, the team looked at rocks containing ancient plant tracks. These traces appear to be sunburned by ultraviolet light, probably the result of a prolonged shortage of ozone in the atmosphere.
“Earth-based disasters such as large-scale volcanism and global warming can also destroy the ozone layer, but evidence for this is not one-sided for the time interval in question,” astronomy and physics professor Brian Fields, lead author, said in a statement. “Instead, we suggest that one or more supernova explosions, about 65 light-years away from Earth, could have been responsible for the prolonged loss of ozone.”
It would have been quite the event, lighting up the skies.
“To put this in perspective, one of the closest supernova threats today is to the star Betelgeuse, which is more than 600 light-years away and well beyond the kill distance of 25 light-years,” said student student. and study co-author Adrienne Ertel added.
The team also looked at other causes of ozone depletion, including meteorite impact, and gamma-ray bursts, but these would not have caused any depletion in the long run.
They suggest that the violent supernova is flooding our planet with dangerous UV, X and gamma rays, and irradiating the ozone layer with effects that could have lasted up to 100,000 years, according to the researchers.
To confirm their suspicions, the team is now looking for the ‘smoke pistol’ – two specific radioactive isotopes of plutonium, dating from the Late Devonian period, which could only come after cosmic explosions on Earth.
“The overarching message of our study is that life on earth does not exist in isolation,” Fields explains. “We are citizens of a larger cosmos, and the cosmos intervenes in our lives – often imperceptibly, but sometimes cruelly.”
READ MORE: An exploding star 65 light-years from Earth may have triggered a mass extinction [Science Alert]
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