The term “planetary nebula” can be confusing because it contains the word “planetary” - which naturally brings to mind the planets in our solar system such as Jupiter, Mars, etc. But a planetary nebula is not a planet at all and has nothing to do with planets or exoplanets. It is a product of an aging star. They are usually ring shaped and are formed by an expanding shell of gas being shed or blown off by the star. They are a type of emission nebula consisting of ionized gases ejected from red giant stars late in their lives. The term originates from the round, planet-like shape of these nebulae. When telescopes were less powerful - these objects looked like planets - hence the term. The first usage of the term may have occurred in the late 18th century by the English astronomer William Herschel. Planetary nebulae are now better understood - but the old term is still used.

Planetary nebulae are formed during the late stages in the life of stars of intermediate mass (1-8 times the mass of our Sun). It is expected that our Sun will form a planetary nebula at the end of its life cycle. Stars running low on hydrogen fuel at the end of their life undergo major changes in their internal processes which results in portions of their mass being blown off into space. These super-hot gases may then become ionized - causing them to produce a variety of different colors depending on the gases present.