A supernova might have killed large sea animals 2.6 million years ago: Study
New Delhi : Since long time, scientists have been trying to explore the affect of supernovae on the Earth. One must know that Supernovae are highly powerful events, depending on how close they are to Earth, they could have consequences ranging from the cataclysmic to the inconsequential. A study reveals that there are specific proofs which link one or more supernova to an extinction of living creatures, some 2.6 million years ago.
Experts say that about 2.6 million years ago supernovae exploded at a distance of 160 light years, away from Earth. At that same time, major extinction called the Pliocene marine megafauna extinction took place on Earth. Up to a third of the large marine species on Earth died at that time and most affected organisms lived in shallow coastal waters.
The research indicates a link between the supernovae and the extinction, and suggests that particles called muons were the guilty parties. The evidence is not only in the fossil record, but in a layer of a radioactive type of Iron deposited on Earth about 2.6 million years ago, called Iron 60. The evidence is also out in space, in the form of an expanding bubble feature created by one or more supernovae.
Lead author Adrian Melott said in a press release that for 15 years he has been studying the effects that supernovae could have on Earth. But this paper is much more specific, and ties the Pliocene extinction to specific supernovae. “This time, it’s different. We have evidence of nearby events at a specific time,” said Melott. “We know about how far away they were, so we can actually compute how that would have affected the Earth and compare it to what we know about what happened at that time — it’s much more specific.”
Melott wrote in the new study, the more radiation the large animal absorbs, the worse is their chance of survival."We estimated the cancer rate would go up about 50 percent for something the size of a human — and the bigger you are, the worse it is," Melott said in a statement. "For an elephant or a whale, the radiation dose goes way up."
The scientists who wrote one of the 2016 papers linked these isotopes to a series of supernovas that occurred between 8.7 million and 1.7 million years ago, erupting about 325 light-years from Earth. According to Melott, that's far enough away to prevent such explosions from seriously damaging our planet, but close enough that Earth would still have been in the path of some cosmic radiation.
Part of this radiation would have taken the form of muons — heavy, electron-like particles that form when cosmic rays collide with other particles in our planet's atmosphere. According to Melott, because a muon is "a couple hundred times more massive" than an electron, it's also more likely to penetrate hundreds of miles underground or deep into the ocean. If lots of muons were to start raining down on the sea during the fallout from a nearby supernova, large sea creatures could have potentially come into contact with huge quantities of these radioactive particles. The resulting radiation might have caused mutations, cancer and mass death, Melott and his colleagues wrote.
Cosmic radiation coupled with other factors like climate change could have been the reason behind the extinction of the giant marine species.
Melott, however, wrote that supernova explosion is just "another piece in the puzzle" that is the Pliocene marine megafauna extinction, and further investigation may be required in near future.