Emission nebula

From South Dublin Astronomical Society

Emission nebulae are clouds of dust and gas which are visible to us due to self-illumination. The elements within the cloud of gas become active due to the energy of nearby hot stars, which causes the gas to glow. As a result, emission nebulae usually appear slightly red similar due to the similar reactions which take place in a neon light. Often, young stars are born within these clouds of gas resulting in a spectacular display of stars with surrounded by clouds of gas and dust. An example of an emission nebula is M42, The Orion Nebula.