Cepheid
/ˈsɛfiɪd/noun
A star that brightens and dims on a strict cycle, used to measure cosmic distances.
The Greek roots
Literally: “one of Cepheus”
The story of the word
The class takes its name from δ Cephei, whose variation John Goodricke found in 1784 while still in his teens; he was dead at twenty-one. Henrietta Leavitt showed in 1912 that the length of the pulse gives away the star's true brightness, which turned Cepheids into the yardstick that measured the distance to other galaxies and settled what those galaxies were. The constellation is named for Cepheus, king in the Perseus story, whose wife Cassiopeia boasted and whose daughter Andromeda was chained to a rock for it.
- How it travelled
- Ancient Greek → Latin → English
- First recorded
- early 20th century
Same family
In a sentence
Hubble found a Cepheid in Andromeda and the universe got much bigger overnight.
Cepheids in the outer arms gave the survey its distance scale.