ABSTRACT

Wood (2006) gives the relative velocity and the distance of 24 galaxies, according to measurements made using the Hubble Space Telescope (see Table 6.2). Velocities are assessed by measuring the Doppler red shift in the spectrum of light observed from the galaxies concerned, although some correction for ‘‘local’’ velocity components is required. Distances are measured using the known relationship between the period of Cepheid variable stars and their luminosity. How can these data be used to estimate the age of the universe?