Emission Nebulae

One type of nebulae we are going to explore are called Emission Nebulae, because they emit their own light. The cloud itself is actually glowing. Within this type of nebula, bright stars inside the clouds energize the atoms in the cloud with ultraviolet radiation. As these atoms fall back to lower energy states, they get rid of the extra energy by emitting it in the form of red light. The process is similar to that of a neon light. This causes the nebula to glow. Emission nebulae tend to be red in color because of the abundance of hydrogen. Additional colors, such as blue and green, can be produced by the atoms of other elements, but hydrogen is almost always the most abundant. A fine example of an emission nebula is the Orion Nebula (M42).

Orion Nebula (M42)