images

Cepheid - artist view

by

Don Dixon/Novapix

Reference

a-eto99-10051

Date

2007-05-14

A Cepheid variable can be used to determine the distances to its host cluster or galaxy. Cepheids are pulsating stars that become alternately brighter and fainter with periods ranging from 10 to 50 days. Astronomers have known for over 50 years that the periods of these stars precisely predict their total luminous power, which allows their distance to be measured.