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 upon 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 as standard candles to measure distances to galaxies. This is because their periods of variability are directly proportional to their luminosities, allowing astronomers to determine their distance based on the amount of light observed. This method has been used to refine our understanding of the size and age of the universe.

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