Variable stars,such as Cepheid variables and RR Lyrae stars,are used in what important measurement in astronomy?
A) Keeping of accurate time
B) Measurement of the gravitational fields of supermassive black holes by their effect on the star's pulsation rate
C) Measurement of the surface temperatures of stars
D) Measurement of distances to galaxies

Question

Quizplus · Accepted Answer

Variable stars, such as Cepheid variables and RR Lyrae stars, are used to measure distances to galaxies through a method known as the period-luminosity relationship. By observing the period and brightness of these stars, astronomers can determine the distance to the galaxy they are located in.

Variable Stars,such as Cepheid Variables and RR Lyrae Stars,are Used