Swan Nebula

Catalog: Messier 17 / NGC 6618

Constellation: Sagittarius

Telescope: 11-inch Schmidt-Cassegrain CPC

Camera: Canon Digital Rebel EOS SL1

Exposure: 30 seconds (I think)

Also known as the Omega Nebula.

This is a nebula, specifically an HII region. There’s tons of cloudy stuff like what you see here all across this image and, indeed, the entire sky. It’s the stuff between the stars, kind of like the stars are rocks in a sandbox. It’s called the interstellar medium. We see a nebula when small regions of it get lit up by nearby stars.