Crab Nebula emits unexplained superflare

Astronomers have observed a massive 'superflare' from the Crab Nebula - but are scratching their heads to try to explain it.

Crab Nebula shocks scientists by dimming

The Crab Nebula  - long thought to be the most stable source of high energy radiation in the sky - has astonished astronomers by showing signs of dimming.