Loop -- "The Aftermath of a Star Blowing Itself Asunder"
This image, taken with the HST's Wide Field and Planetary Camera 2, shows
a region of gas and dust about 2500 light years away in the constellation
Cygnus, the Swan (which is high overhead in late summer). The glowing
gas is the result of a shock wave from an exploding star, or supernova,
that occurred about 15,000 years ago. The blast wave is moving through
the cloud, compressing and heating the gas and so is causing it to glow.
If the gas in this image was bright enough to be seen by the naked eye,
it would cover an area in the sky equal to about 6 times the area of the