A glance at the night sky above Earth shows that some stars are much brighter than others. However, the brightness of a star depends on its composition and how far it is from the planet. Astronomers ...

Cepheid distances are determined through the so-called inverse-square law of light, which tells astronomers how a star’s apparent brightness diminishes with distance. If a star appears to have a ...

Cepheid variables are a type of star that undergo regular pulsations. The length of a Cepheid’s pulsations is always related to its intrinsic, or absolute, brightness in a simple way: The longer its ...