The 5 Types of Nebulae
For thousands of years, humans have been intrigued by mystical nebulae, beautiful clouds of dust and gas adrift in space. From these thousands of years of curiosity and subsequent research, scientists have determined that there are five types of nebulae.
The five types of nebulae are planetary nebulae, emission nebulae, reflection nebulae, dark nebulae, and supernova remnants, which vary for numerous reasons.
Interestingly, planetary nebulae have almost nothing to do with planets or exoplanets. Instead, these nebulae consist of a glowing and expanding shell of gas, ejected from red giant stars late in their lives. Planetary nebulae possess a ring-like shape from this emission of gas.
An emission nebula is unique in that it shines with its own source of light. Similarly to a planetary nebula, emission nebulae form from ionized gases. They differ in that emission nebulae that emit light of various wavelengths, while planetary nebulae do not. Emission nebulae tend to emit a reddish color as a result of the abundance of hydrogen in them.
Like an emission nebula, reflection nebulae also shine through the darkness of space, just not with their own light. True to its name, a reflection nebula does not create its own light but instead shines by reflecting the light of nearby stars. Reflection nebulae are created when the energy from a nearby star is insufficient to create an emission nebula but is enough to make the dust visible.
The most mysterious of all nebulae are dark nebulae. These unique nebulae are so dense in gas that they obscure visible wavelengths of light, meaning that we are unable to see them, explaining why they are also called absorption nebulae. Because of this absorption, to us, dark nebulae just look like dark masses blotting out the stars of space.
A supernova remnant is a structure that results from the explosion of a star or a supernova. A supernova remnant is held together by an expanding shock wave and consists of ejected material of the star that expands from the explosion and interstellar material the shockwave sweeps up along the way.