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What is a supernova?

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Quick answer

A supernova is the colossal explosion of a dying star, briefly outshining an entire galaxy. It happens when a massive star runs out of fuel and collapses, or when a white dwarf is tipped over a mass limit — scattering elements across space.

Key things to understand

  1. It's the explosive death of a star.
  2. Massive stars explode when their core collapses after running out of fuel.
  3. The blast can briefly outshine billions of stars.
  4. It forges and scatters heavy elements like gold and iron.
  5. It can leave behind a neutron star or a black hole.

People also ask

What causes a supernova?
Either a massive star's core collapsing when it exhausts its fuel, or a white dwarf gaining too much mass and detonating.
Why are supernovae important?
They forge heavy elements and scatter them into space, seeding future stars, planets, and even the atoms in our bodies.
What's left after a supernova?
Often a dense neutron star or, for the most massive stars, a black hole, surrounded by an expanding cloud of debris.