How quickly does a supernova happen?

Catch a failing star: the tense wait for a supernova, Supernovae

A warning system for when stars go supernova

Supernova

Know Your Novas: Star Explosions Explained (Infographic)

How Quickly Does A Supernova Happen? The Stunning Speed of a Core Collapse Supernova

Astronomy & Astrophysics 101: Supernova

Astronomers Watch a Supernova and See Reruns - The New York Times

What's a safe distance from a supernova for Earth?

How Close a Supernova Needs to Be to Destroy Life on Earth