This Jaw-Dropping ‘Supernova Explosion Nebula’ May Have Collided With Something Say Scientists - Forbes

Cassiopeia A is the remnant of a once massive star that died in a violent supernova.

The many sides of the supernova remnant Cassiopeia A. Located 10,000 light-years away in the ... [+] northern constellation Cassiopeia, Cassiopeia A is the remnant of a once massive star that died in… [+3583 chars]

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