Q&A: Normal Stars, White Dwarf Stars, and Star Clusters

Q:
The term "Planetary Nebula" seems misleading. Why are they called that?

A:
The definition of the term "planetary nebula" is historically correct, but the term is a misnomer. Some planetary nebulas appeared to look like giant planets, specifically Uranus, when viewed through a small telescope by William Herschel, who coined the term. Astronomy is a very old field of study, so historical artifacts like this are not rare.

Planetary nebulas are really shells of gas cast off by evolved, Sun-like stars. The Sun should experience this phase in a few billion years.