Near-Earth supernova

A near-Earth supernova is an explosion that happens when a star dies. This explosion can occur close to the Earth, within about 33 to 978 light-years. Because it happens close by, such an explosion can affect life and the environment on our planet. These explosions are very powerful and mark the end of a star’s life.

Scientists think that about 20 supernova explosions have happened within 300 parsecs (about 978 light-years) of the Earth in the last 11 million years. These explosions often happen in areas where new stars are being born. Today, there are about 12 stars that might become near-Earth supernovas in the future.

Learning about these events helps us understand how stars live and die, and how such cosmic explosions might influence our solar system. For more information about how people have observed these explosions in history, see the History of supernova observation.

Effects on Earth

A supernova explosion happens close enough to Earth to have effects roughly every 240 million years. The main danger is from gamma rays, a type of high-energy light. These rays can change molecules in Earth’s upper atmosphere, especially oxygen and nitrogen. This can harm the ozone layer, which protects Earth from harmful solar and cosmic radiation.

In the past, explosions from nearby stars might have changed Earth’s climate. These events sent more cosmic rays toward Earth, leading to cooler temperatures and stronger winds. This mixing brought more nutrients to shallow ocean waters, helping more life grow. One famous star, Betelgeuse, might explode in the future, but it would likely take millions of years.

Risk by supernova type

A nearby supernova is an explosion from a dying star. If it happens close enough to Earth, it could cause problems.

Some big stars that might explode in the next 1,000 years are within a few hundred light years of us. Even if they explode, they probably won’t harm Earth much.

If a Type II supernova happens within about 26 light-years, it could damage Earth’s ozone layer. Scientists study how radiation from past supernovae, like SN 1987A in the Large Magellanic Cloud, might affect our planet. Type Ia supernovae could be more dangerous if they happen very close to Earth, but we don’t know when or where they will occur.

Past events

A nearby supernova helped shape the Solar System about 4.5 billion years ago. Over time, supernovae have created the heavy elements needed for life on Earth.

Scientists have found signs of past supernovae in rocks on Earth, including a special type of iron called iron-60 in deep-sea rocks of the Pacific Ocean. This suggests a supernova happened relatively close to our solar system in the last few million years.

In 1998, a supernova remnant called RX J0852.0−4622 was discovered. If it was as close as some scientists believe—about 650 to 700 light-years—it would be a rare event.