The Flying Bat & Squid Nebulae

The Flying Bat Nebula, cataloged as Sh2-129, is a large, relatively faint emission nebula located in the constellation Cepheus, about 2,300 light-years from Earth. It lies close to the brighter and more commonly imaged IC 1396 nebula, home of the Elephant’s Trunk Nebula and spans over 2.5 degrees across the sky — about five times the apparent diameter of the full Moon — making it visually impressive but challenging to observe due to its faintness.

Sh2-129 is primarily an H-alpha emission nebula, meaning its reddish glow is produced by ionized hydrogen atoms. Inside Sh2-129 is the remarkable Squid Nebula (Ou4), emitting a striking blue-green light due to doubly ionized oxygen (O-III), forming a very faint, bipolar structure that stretches nearly 50 light-years in length.

HR 8119, the bright star at the center of Ou4, is a hot, massive triple star system and may have launched the outflow that created the Squid Nebula approximately 90,000 years ago. This region also contains a small mixed emission and reflection nebula, vdB 140, further adding to its complexity.