The Origin of the Universe
A survey of the evidence
Introduction
Measurement Overview
Parallax Distances
Star Sizes and Absolute Magnitudes
Cepheid Distances
Type 1a Supernovae Distances
Redshift Velocities and Distances
Age of the Stars in Globular Clusters
The Oldest White Dwarfs
The Cosmic Microwave Background
Conclusion
Astronomers understand stellar energy production processes. They understand how a star's luminosity is related to its size. They understand how a star's spectrum is related to its temperature. From a star's parallax distance, temperature and luminosity they can calculate its absolute magnitude - the brightness it would have, if it were a fixed distance from us. Astronomers have determined the size and absolute magnitudes of millions of nearby stars.