Cass A, VLA
Cass A is a supernova remnant in our own Galaxy. This is the remnant of a star which exploded in ???? Since then, the material thrown off in the explosion has been expanding and interacting with the surrounding gas. It is this interaction which produces the fine structure seen in the shell.

This image was made using a collection of radio telescopes known as the Very Large Array (VLA), situated in New Mexico in North America. This telescope makes images using electromagnetic radiation in the radio part of the spectrum. They use frequencies slightly different to those you listen to on your radio at home.

Image credit: VLA, NRAO