A supernova may have caused Earth’s mass extinction 359 million years ago

There was supposed to be an Earth-shattering kaboom!

There are different forms of supernova explosions, and this event was the result of a supermassive red giant star collapsing in on itself at the end of its life. The best-known red giant star, Betelgeuse, recently went through a period of dimming. This event is now thought to be the result of the star releasing a cloud of material which temporarily blocked light from reaching Earth. Life on Earth cold be wiped out entirely by the explosion of a red giant star within 25 light years of our home planet. Fortunately for us, the nearest red giant, Gacrux, sits at a comfortable distance of 88 light years from our home world.

“…[O]ne of the closest supernova threats today is from the star Betelgeuse, which is over 600 light-years away and well outside of the kill distance of 25 light-years,” University of Illinois (U of I) graduate student Adrienne Ertel stated.

Ozone depletion can be the result of various environmental triggers, but other causes do not match with details seen in the geological record of the time. The research team explored the impact of meteorites, solar eruptions, and gamma ray bursts (GRB’s) on the environment of the ancient Earth. Virtual models revealed losses of ozone around the world.

“But these events end quickly and are unlikely to cause the long-lasting ozone depletion that happened at the end of the Devonian period,” Jesse Miller, a graduate student at the U of I stated.

Unlike these other events, supernovae deliver a powerful one-two punch that can devastate the environment. The initial explosion bathes our planet in ultraviolet radiation, X-rays and gamma rays. Then, a powerful blast of supernova debris slams into the Solar System, releasing a persistent display of cosmic rays that can flood Earth with radiation, destroying the ozone layer of the Earth for 100,000 years.

Pictured is a simulation of a nearby supernova colliding with and compressing the solar wind. Earth’s orbit, the blue dashed circle, and the Sun, red dot, are shown for scale. Image credit: Jesse Miller

“Here we study an alternative possible cause for the postulated ozone drop: a nearby supernova explosion that could inflict damage by accelerating cosmic rays that can deliver ionizing radiation for up to [100,000 years]. We therefore propose that the end-Devonian extinctions were triggered by supernova explosions at [65 light years distance], somewhat beyond the ‘kill distance’ that would have precipitated a full mass extinction,” researchers wrote in the Proceedings of the National Academy of Sciences of the United States of America (PNAS).