(via APOD: 2012 January 9 - Facing NGC 6946)
First a meteor, then a star, now how about a galaxy. I can’t help it, the Fireworks Galaxy is awesome in this shot from the Subaru Telescope on Mauna Kea. Why the “fireworks”?
Take a look at the colors here. Some of them are slightly over-emphasized, but they are realistic to an extent. The yellower area toward the galactic center is full of older main-sequence stars, the outer parts of the spirals show clear indicators of a whole lot of gas and dust, which means a lot of star formation. That also means that you can form a lot of short-lived stars (on a stellar time-scale, anyway) that tend to explode in a supernova. Per the APOD editor, nine supernovae have been observed in NGC 6946 since the beginning of the 20th century.
In the same vein, if you look at all the pink areas, those are places where dust is collapsing in to form new stars. New stars can get big and bright and oversized very easily.
Composite Image Data - Subaru Telescope (NAOJ) and Robert Gendler; Processing - Robert Gendler