Did a Nearby Supernova Shower Earth with Cosmic Rays Millions of Years Ago?

A team of astronomers has uncovered a possible link between Earth’s ancient past and the Sun’s journey through the Milky Way. Geologists first detected an unusual spike of beryllium-10 in Pacific Ocean crusts, a rare isotope not produced by natural processes on Earth. The discovery led researchers to investigate cosmic sources for the beryllium-10, which forms when cosmic rays strike our atmosphere. Using data from the Gaia space probe, the team tracked the movements of the Sun and 2,725 star clusters over the last 20 million years.

They found that between 10 and 11.5 million years ago, the Sun passed near several massive star clusters in the Orion region. One cluster, ASCC 20, came within roughly 110 light-years of the Sun. This cluster contained stars so large they were destined to explode as supernovae.

Such an event would have been visible from Earth but not necessarily harmful to life. The explosions likely showered our planet with cosmic rays, creating the beryllium-10 detected in ocean crusts. The study connects Earth’s geological record with the solar system’s path through the galaxy. It shows how close encounters with star clusters may have left lasting traces in our planet’s history. The findings also demonstrate how astronomy and geology can work together to reveal Earth’s cosmic past.