The Cygnus Loop
The shockwave from a 20,000 year-old supernova
in the constellation of Cygnus
supernova explosion is
still expanding into interstellar space.
The collision of this fast moving wall of gas with
a stationary cloud has heated it causing it to
glow in visible as well as
high energy radiation, producing the nebula known as the
Cygnus Loop (NGC 6960/95).
The nebula is located about 2500 light-years away.
The colors used here indicate emission from
different kinds of atoms excited by the
shock:
oxygen-blue, sulfur-red, and hydrogen-green.
This picture was taken with
the Wide Field and Planetary Camera 2 on board the
Hubble Space Telescope.