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Supernova
Astronomical Event
Supernova refers to an event in space, not something on Earth, relating to the end of a star's life cycle. 
Cataclysmic Brightness
A supernova is noted for its intense brightness, outshining entire galaxies for a short time. 
Explosive End
Supernova implies a violent, destructive ending of a star, but it's a natural part of the universe. 