ABSTRACT
In the period 1912 to 1929, astronomers undertook spectral analysis of the light from distant galaxies. It was discovered that as a result of the Doppler
effect, the positions of spectral lines were displaced towards the red end of the spectrum, implying that the galaxies were moving away from the Earth at incredible speeds. In 1929, Hubble found that the shift in the spectral lines, and hence the velocity of recession of the galaxy, was dependent directly on the distance the galaxy was away from the Earth. That is, galaxies are moving away from each other, the further away, the greater their speed.
