— Nomad, from Star Trek “The Changeling”
While reading “Entering Space” by Robert Zubrin, I chanced upon the subject of stellar classification. The Morgan-Keenan system goes from O-type, the hottest, to M-type, the coolest (Red dwarfs). Our own sun, Sol, is an example of a G-type star, which are on the cool side yet still hot and bright. Later, other types have been added, for example White Dwarfs are known as D-types. If humankind will someday journey to remote stars, it’s best to memorize this handy list!
The Morgan-Keenan system is as follows:
This is sometimes remembered by the mnemonic “O be a fine gal/guy, kiss me.”