Diocese definition, an ecclesiastical district under the jurisdiction of a bishop. See more.
planetary nebulae represented here by the ring nebula are examples of emission nebulae an emission nebula is a nebula formed of ionized gases that emit light of various colors the most common source of ionization is high energy photons emitted from a nearby hot star
Nebula. Nebulae are large collections of interstellar gas and dust particles. Most nebulae can be interpreted as a denser region of the interstellar medium accreting under gravity; others are remnants of stars after the end of their lifetime. They mainly consist of hydrogen and helium.