Rampaging Fronts of the Veil Nebula

A supernova explosion of a high-mass star results in fast moving blast waves.
At the front of the waves shown above, ionized gas in the Veil Supernova Remnant rushes
out from the explosion, sweeps up material, and breaks up many atoms into constituent
ions and electrons. Observations with the Hubble Space Telescope in 1993 indicate that
the blue shock wave was catapult away from the stellar explosion after the red shock
wave and has yet to catch up to it in some regions. The Veil supernova remnant's has
a very large angular size - six times the diameter of the full moon - and different parts
of it are known as the "Cygnus Loop" and catalog numbers NGC 6960, NGC 6979,
NGC 6992, and NGC 6995.