Tree rings on Earth indicate the influence of distant supernovae

Powerful cosmic explosions occurring thousands of light-years from Earth could have left geological and biological traces on our planet, according to new research by Robert Brakenridge, a geologist at the University of Colorado in Boulder, USA.

This study examines the effects of supernovae, which are some of the most powerful explosions in the universe. For just a few months, one exploding star can release as much energy as the Sun gives off throughout its entire life cycle.

A supernova very close to us could wipe out human civilization from the face of the Earth. However, more distant stellar flares also affect our planet, bathing it in streams of hazardous radiation and destroying the ozone layer, Brackenridge says. During this period, under the influence of cosmic radiation, a change in the structure of a number of atoms, including the carbon atom, occurs on the Earth, and the resulting radioactive atoms can be fixed by studying the biological material accumulated during this period, which in the modern era is already carbon deposits.

To investigate this possible effect, Brackenridge examined tree rings for signs of radioactive carbon. To his surprise, by correlating a list of nearby supernovae with periods during which unexplained peaks corresponding to increased radioactive carbon were observed in tree rings, Brecknridge found a number of close matches. According to these findings, relatively nearby supernovae may have caused major climate changes on Earth over the past 40,000 years.

At this stage of the work, the conclusions drawn cannot be called unambiguous, but they make us think about how deeply cosmic events affect the stability of the existence of life on Earth, Brackenridge noted.

The study is published in the International Journal of Astrobiology.

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