Planetary nebula

Uncommon card · No. 102299

A planetary nebula is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives. "Planetary" describes their planet-like round shape as observed through early telescopes, but they are unrelated to planets. As early as the 1780s, the English astronomer William Herschel described them as resembling planets; in January 1779, the French astronomer Antoine Darquier de Pellepoix had described the Ring Nebula as "very dim but perfectly outlined; it is as large as Jupiter and resembles a fading planet". All planetary nebulae form at the end of the life of a star of intermediate mass, about 1-8 solar masses. It is expected that the Sun will form a planetary nebula at the end of its life cycle. They are relatively short-lived phenomena, lasting perhaps a few tens of millennia, compared to considerably longer phases of stellar evolution. Once all of the red giant's atmosphere has been dissipated, energetic ultraviolet radiation...

Read on Wikipedia · Image Pablo Carlos Budassi, CC BY-SA 4.0