Red Shift

• Light appears red shifted from galaxies which are moving away from Earth
• The change with distance of each galaxy's speed is evidence of an expanding universe
• At the start of the Big-Bang, as the universe expands:

  • Distance from the galaxies also expands
  • Light from a galaxy has its wavelength 'red-shifted' as it appears to move away from us
  • As wavelength appears to get larger frequency appears to decrease.