Supernovas are created during the last moments of a star's life. These gigantic explosions can wipe out galaxies and the planets inside them.

What would happen if there was a supernova in our galaxy?

X-rays and more energetic gamma-rays from the supernova could destroy the ozone layer that protects us from solar ultraviolet rays. It also could ionize nitrogen and oxygen in the atmosphere, leading to the formation of large amounts of smog-like nitrous oxide in the atmosphere.

Can galaxies go supernova?

Astronomers believe that about two or three supernovas occur each century in galaxies like our own Milky Way. Because the universe contains so many galaxies, astronomers observe a few hundred supernovas per year outside our galaxy. Space dust blocks our view of most of the supernovas within the Milky Way.