New research suggests that powerful supernova explosions in our cosmic neighborhood may have triggered at least two of Earth’s most devastating extinction events. These findings add weight to the theory that celestial forces have played a significant role in shaping the planet’s biological history.
Supernovae are the explosive deaths of massive stars, unleashing immense radiation and high-energy particles. If such an event occurred close enough to Earth, it could strip away the ozone layer, exposing life to lethal ultraviolet (UV) radiation. This mechanism has long been considered a possible cause of past extinction events, but a new study led by astrophysicist Alexis Quintana from the University of Alicante strengthens this link.
By analyzing the rate of supernovae in our galaxy, Quintana and his team found that their timing aligns with two of Earth’s most catastrophic mass extinctions: the Late Ordovician (445 million years ago) and the Late Devonian (372 million years ago). These periods saw the disappearance of vast numbers of species, with evidence pointing to a severe depletion of the ozone layer.
Cosmic Forensics: Tracking Past Supernovae
To test the plausibility of a supernova-driven extinction, researchers examined a census of massive OB-type stars—short-lived but incredibly energetic stars that frequently end their lives in supernova explosions. The team focused on stars within a 3,260-light-year radius of the Sun, determining that at least 24,706 OB stars exist within this range.
Using this data, they calculated that supernovae occur at a rate of 15 to 30 per million years across the Milky Way. However, for an explosion to significantly impact Earth, it must occur within about 65 light-years. Based on their findings, the researchers estimated that such close-proximity supernovae occur roughly 2.5 times per billion years—matching the timeline of the Ordovician and Devonian extinctions.
How a Nearby Supernova Could Reshape Earth’s Ecosystem
A supernova within 65 light-years would bombard Earth with cosmic rays, potentially destroying atmospheric ozone and allowing dangerous levels of UV radiation to reach the surface. This would disrupt ecosystems, severely damaging plant life and marine organisms at the base of the food chain, ultimately leading to a mass extinction.
Notably, previous research has found spikes of radioactive isotopes such as iron-60 in Earth’s geological record—an element produced in supernova explosions. These discoveries further suggest that our planet has been directly exposed to supernova debris in the past.
Should We Be Concerned About Future Supernovae?
At present, no nearby stars are poised to explode within a dangerous range. The well-known red giants Betelgeuse and Antares are approaching the end of their lifespans, but they are located hundreds of light-years away—far enough that their eventual explosions will pose no threat to Earth.
Of course, cosmic disasters aren’t the only extinction threats humanity faces. Large asteroid impacts and massive volcanic eruptions are also capable of triggering global devastation. While we have little control over these cosmic events, understanding their effects can provide deeper insight into Earth’s history and the forces that shape life.
