What is a Planetary Nebula?
Planetary nebulae are the ejected diffuse gas given off by a low mass star at the end of its life. In the red giant phase these stars will begin to expand, burning through their remaining fuel and eventually collapsing dispersing a large shell of gas. The name 'Planetary Nebula' is a misnomer coined by british astronomer, William Herschel. After discovering Uranus, Herschel believed these objects had resembled the newly found gas giant and labeled them accordingly. The first planetary Nebula to be discovered, The Dumbbell Nebula, was done so by french astronomer, Charles Messier, listing it in his catalog as Messier 27.