About 11,000 years ago a star in the constellation of Vela exploded. This bright supernova may have been visible to the first human farmers. Today the Vela supernova remnant marks the position of a relatively close and recent explosion in our Galaxy. A roughly spherical, expanding shock wave is visible in X-rays.

The explosion is over but the consequences continue. About eleven thousand years ago a star in the constellation of Vela could be seen to explode, creating a strange point of light briefly visible to humans living near the beginning of recorded history.

What happens when a star explodes? A huge fireball of hot gas shoots out in all directions. When this gas slams into the existing interstellar medium, it heats up so much it glows in X-rays.