Standard Candles

Getting distances to galaxies

MethodReliabilityGalaxy TypeDistance Range
(millions of light years)
Cepheids and RR LyraeVerySpirals,Irregularsup to 65
Bright StarsModerateSpirals,Irregularsup to 150
Planetary nebulaVeryAllup to 70
NovaModerateAllup to 100
Globular ClustersModerateAllup to 100
Surface Brightness fluctuationsVeryEllipticalsup to 100
Tully-Fisher MethodVerySpirals,Irregularsup to 300
Type I SupernovaVeryAllup to 8,000
Brightest Galaxy in ClusterVeryEllipticals70-13,000
Hubble's LawVeryAll300-13,000