A shock wave from this catastrophic event expands into space, followed by a shell of material from the star's atmosphere. The material blown off contains chemical elements created throughout the star's lifetime. Debris from supernovas enriches the chemistry of interstellar space with material that becomes part of new stars and planets. Supernovas are rare phenomena fewer than five supernovas in our Milky Way galaxy have been visible from Earth in the last 1,000 years.
Some supernovas can be bright enough to see with the naked eye during the day.
They may continue glowing for several weeks or even months after the explosion. Thick clouds of interstellar dust hide some supernovas, but astronomers can detect those by the radio waves that the supernova emits. Supernovas occur in all galaxies, not just the Milky Way. Supernovas that occur outside the Milky Way are bright enough to stand out against the other stars in the galaxy. However, they are usually not bright enough to pick out without a telescope .