The Bubble Nebula (NGC 7635, Caldwell 11, Sh2-162) is an emission nebula in Cassiopeia. In this image it is being photobombed by open cluster M52 in the lower right corner. Though the Bubble is a relatively small nebula it is surrounded by large clouds of gas. Indeed the bubble itself is caused by the stellar wind of its central star running into that surrounding gas cloud.

The Bubble is 7-11 though sand light years away.

Though this image makes it look as if the Bubble is shining through a dense cloud, in reality the cloud is very diffuse. But the same light that excites the emission for the Bubble excites the rest of the cloud but that light has spread so much by that point the cloud is illuminated only dimly.

This is 11h 30m of SHO data. For all the technical details, see astrobin.