This image shows a beautiful portion of the Veil Nebula - the shattered remains of a supernova that exploded some 5-10 000 years ago. The intertwined rope-like filaments of gas result from the enormous amounts of energy released as the fast-moving debris from the explosion ploughs into its surroundings and creates shock fronts.
The image displays two characteristic features: sharp filaments and diffuse emission. These correspond to two different viewing geometries: sharp filaments correspond to an edge-on view of a shock front, and diffuse emission corresponds to a face-on view of it.
This image is a small portion of the Veil located in the western part of the Veil (to the left in the overview image). The entire structure spans about 3 degrees, corresponding to about 6 full moons.
The image was taken with the Wide Field and Planetary Camera 2 (WFPC2) on board the Hubble Space Telescope. The colour is produced by composite of three different images. The different colours indicate emission from different kinds of atoms excited by the shock: blue shows oxygen, green shows sulphur, and red shows hydrogen.
Image Credit: NASA, ESA, and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration
Explanation from: https://www.spacetelescope.org/images/heic0712c/