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document updated 16 years ago, on Sep 11, 2008
distance ladder
,
distance scale
really good explanation
Methods
trigonometric parallax
standard candle
spectroscopic parallax
planetary nebula luminosity function
surface brightness fluctuation
RR Lyrae variable
tip of the red giant branch
Tully-Fisher relation
redshift
Units
unit
method
equivalent
AU
150,000,000 km
ly
63,000 AU
parsec
3.3 ly
z=
redshift
z has
several things that have to be factored out
before it can be used as a direct distance
km/s
redshift
68.8 - 71.4 mpc, 227 - 235 ly