Do Supernovae Pose a Threat to Life on Earth? - 2023

Astrogeology, Asteroids, Robots, Space Flight & Extraterrestrial Matters / Astrophysicists/Astrogeologists and their Work

[Note: This report has been edited by the editors to eliminate the unnecessary fear-pandering contained in the original article, which should have been flagged by the editors of Interesting Engineering.]

Chacko reported in mid-April, 2023 that scientists have discovered that supernovae, one of the most powerful events in the universe, can be a threat to life on planets like Earth that are in range due to their intense X-rays. Supernovae are one of the most vigorous and visually stunning events in the universe, capable of briefly outshining galaxies. However, a new NASA study has identified that they could pose a threat to life on planets in range of the supernova.

Astronomers have analyzed data collected from the Chandra X-ray Observatory and other telescopes and concluded that intense X-rays from exploded stars can affect planets over 100-light years away. A large dose of X-rays is produced when a supernova’s blast wave infuses into dense gas surrounding the exploded star. These X-rays travel through space for months, years and even decades and can reach planets conducive to life to trigger extinction events to any biologic life on those planets.

                                                                          An illustration of supernova effects immediately after and decades later.

The study, authored by Ian Brunton, Connor O’Mahoney, and Brian Fields from the University of Illinois at Urbana-Champaign; Adrian Melott from the University of Kansas; and Brian Thomas from the Washburn University in Kansas, was published in the April 20, 2023 issue of the Astrophysical Journal. The team studied X-ray observations of 31 supernovae and their aftereffects as captured by NASA’s Chandra X-ray Observatory, the Swift and NuSTAR missions, and the European Space Agency’s XMM-Newton. They showed that radiations can travel as far as 160 light-years, and can penetrate planets with lethal doses on the way.

[The NASA report actually said: "There is strong evidence — including the detection in different locations around the globe of a radioactive type of iron — that a supernovae occurred "close" to the Earth between about 2 million and 8 million years ago. Researchers estimate these supernovae were between about 65 and 500 light-years away from Earth. Although the Earth and the Solar System are currently in a safe space in terms of potential supernova explosions, many other planets in the Milky Way are not. These high-energy events would effectively shrink the areas within the Milky Way galaxy, known as the Galactic Habitable Zone, where conditions would be conducive for life as we know it."]

The authors of the research took a novel approach from most previous studies, and focused on the immediate aftermath of a supernova explosion and the energetic particles that arrive hundreds to thousands of years later. When a planet is infiltrated by radiation of this intensity, its atmospheric chemistry could be severely affected. If a supernova was close enough, in Earth’s case, this could even wipe out a portion of ozone, without which organisms - particularly those at the foundation of the food chain - would not survive and could trigger a chain of reactions up the food chain, leading to an extinction event.

Years of exposure to these X-rays and the impact of ultraviolet radiation from the planet’s host star would produce nitrogen dioxide causing a brown haze in the atmosphere. The team concluded that a “de-greening” of land masses could also occur. Although a lack of potential supernova progenitors within 160-light years rules out an immediate threat on Earth, X-ray exposure- to a similar degree- might have occurred in the past. Additionally, many other planets in the Milky Way, including ones we are hopeful of being habitable, are not yet out of danger.

“Further research on X-rays from supernovae is valuable not just for understanding the cycle of stars, but also has implications for fields like astrobiology, paleontology, and the earth and planetary sciences,” said Brian Fields, advocating for follow-up observations of interacting supernovae.