Supergiants are some of the largest stars in the universe. They are larger than giant stars, and less luminous than hypergiants. They vary greatly in size. They tend to be situated towards the top of the Hertzsprung-Russel Diagram, which is a graph depicting star development. Some are only 50 million kilometers across, small enough to fit inside the orbit of Venus. Some are 2,700 million km across, as wide as the orbit of Neptune.
- Schuster, Michael Thomas. (2007). Investigating the circumstellar environments of the cool hypergiants. ISBN 978-0-549-32782-0. OCLC 1194750619.