Emission nebula NGC 7380 surrounding a diffuse open star cluster. Emission nebulae (HII regions) are clouds of gas which glow as hydrogen gas they contain is ionised by radiation from hot stars within them. The star cluster is thought to be is very young, only around 4 million years old. It formed from coalescing gases from the nebula. This system lies around 12,000 light years from Earth in the constellation Cepheus. It was discovered in 1787 by Caroline Herschel.