According to reports, in the latest issue of the Proceedings of the National Academy of Sciences, Fields, an astronomy professor from the University of Illinois in the United States, after a large number of data analysis and his research team, believes that the second mass extinction that occurred 359 million years ago may be related to a supernova explosion.
Second mass extinction
During the transition period between the Devonian and Carboniferous Periods, the second mass extinction occurred on The Earth, and the marine life on the Earth ushered in the catastrophe, but after the second mass extinction, the Earth also entered a new era of rapid evolution of species.
The Devonian is the "fish age" on the earth, the ancestors of reptiles and amphibians, all appeared in the Devonian Period, in the previous archaeological research, scientists found that the climate on the earth during the Devonian period was very humid and warm, even in the polar regions, at that time it was also the four seasons like spring.
However, the strange thing is that at the end of the Devonian Period, the earth suddenly "changed its face", and the entire earth's climate environment has undergone great changes, the main change is manifested in the sudden drop in temperature, the sea water has receded and frozen into ice, so marine life has also ushered in the disaster.
According to statistics, in the second mass extinction, a total of 72% of species have become history. As for the cause of the mass extinction, in 1969, a paleontologist from Canada believed that it was related to the impact of an asteroid on Earth, a conjecture that has been widely accepted by the scientific community for many years, but in fact, it lacks key evidence.
The cause of the second mass extinction?
Why is there a lack of evidence for the claim that the asteroid hits the Earth? We all know that the most recent mass extinction we have, through research, scientists generally believe that it was caused by asteroids hitting the Earth, and in geological tests, a large number of radioactive isotopes and giant craters have also been found as evidence
However, no evidence of the second mass extinction caused by an asteroid impact on Earth, whether from giant craters in the late Devonian period or radioisotopes that can be shown to be associated with the impact, has been found, so scientists have been looking for other causes for years.
Until some time ago, fields, a professor of astronomy, and his research team, while studying fossils and rocks from the second mass extinction period, found that the plant spores had been sunburned by strong ultraviolet rays.
We all know that a very important reason why the earth is habitable is that the earth's atmosphere, especially the ozone layer, blocks all kinds of radiation from space for us, and also reduces the ultraviolet rays of the sun.
However, plant spores from the late Devonian period indicate that there was a long period of absence of the ozone layer on Earth at that time, and Professor Fields believes that this may be the key reason for the second mass extinction of the Devonian.
Supernovae have occurred around the solar system
Professor Fields speculated that at the end of the Devonian Period, about 65 light-years away from Earth, there had been a supernova explosion, and the energy it released caused serious damage to the Earth after reaching it, and the Earth's ozone layer was destroyed.
For a long time after that, the radiation received by the earth continued to increase, eventually leading to a mass extinction on the earth, and it was not until about 100,000 years later that the earth began to gradually return to a healthy state.
How scary are supernova explosions? The study believes that if a supernova explosion occurs within 1,000 light-years from The Earth, it is like an exploded "bomb" for the Earth.
Although the supernova explosion will not immediately destroy life on the earth, but it will destroy the earth's atmospheric structure, a large number of gamma rays are released with the supernova explosion, if it is close to the earth, then after arriving on the earth, it will trigger a series of chemical reactions, the earth's ozone layer is consumed.
In this way, life on Earth will be completely exposed to the harm of the solar wind, cosmic rays, etc., and it will not take too long to become extinct one after another. This is one of the reasons why scientists have been very worried after the discovery of the Antarctic ozone hole, because if the ozone hole appeared in a densely populated area, the impact would be unpredictable.
Therefore, after collecting relevant evidence this time, scientists will think that the second mass extinction is related to the supernova explosion.
Of course, if you want to completely unravel the mystery of the second mass extinction, you still need a lot of evidence, and in the next step, scientists also hope that through archaeological excavations, the existence of radioactive isotopes can be found in the relevant fossils of the late Devonian period.
In particular, plutonium-244 and samarium-146, two isotopes themselves can not be found on Earth, only through the cosmic explosion, especially the terrible supernova explosion around the Earth, will reach the Earth, into the geology of the Earth.