Distance Measurements to Other Galaxies (II): The
Hubble Law
E. Hubble (1913):
Distant galaxies are moving away from our Milky Way, with a recession velocity, vr, proportional to their distance d:
vr = H0*d
H0 ≈ 70 km/s/Mpc is the Hubble constant.
=> Measure vr through the Doppler effect ® infer the distance.
