Could an exploding star kill all life on Earth?

We find out if a supernova could kick-start a mass extinction

A supernova is a large explosion that takes place at the end of a star's life cycle. Image Credit: NASA

A supernova is a large explosion that takes place at the end of a star’s life cycle. Image Credit: NASA

Asked by James Haughty

If it was close enough, then yes. Astronomers predict that if a supernova were to explode within 30 light years of us, a mass extinction would be possible. X-rays and the more energetic gamma rays brought about by a star’s explosion would destroy Earth’s ozone layer and ionise nitrogen and oxygen in the atmosphere, leading to the formation of large amounts of smog-like nitrous oxide in the atmosphere. Supernovae occur every 100 years in the Milky Way.

Since our galaxy is a large place though, and since the Sun is located near the outskirts of the Milky Way where few stars are massive enough to explode as a supernova, having one go off within 30 light years off us should, on average, happen only once every 100 million years.

Answered by Sophie Allan at the National Space Centre

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