Two galaxies orbiting each other Galaxies orbiting within a cluster of galaxies. Indistinguishable from the general expansion. Most galaxies are receding from us. Measured accurately from spectral lines shifts. Peculiar velocities can affect observed v Mapping the Universe Can map the distribution of galaxies using redshifts.
Relative distances are OK, but absolute scale is still poorly known.
1998 February 20 Copyright 1998 Richard W. Pogge, All Rights Reserved.