It's essentially built up of a chain or ladder. From parallax measurements to cepheid variables to supernova. This might give a good introduction http://www.iop

It's essentially built up of a chain or ladder. From parallax measurements to cepheid variables to supernova. This might give a good introduction http://www.iop.org/resources/topic/archive/cosmic/ http://www.iop.org/resources/topic/archive/cosmic/