1. Large-Scale Structure in the Universe Superclusters, walls, and voids dominate the large scale structure of the Universe

2. Hubble’s Law velocity of galaxy = H o d =(Hubble’s constant) (distance to the galaxy)

3. The Doppler Shift Christian Doppler 1842: the observed wavelength of an object is affected by its apparent motion Doppler shift occurs when the source of the waves is moving with respect to the observer occurs for all waves (e.g. water, sound, light)

4. Units: 1 nanometer= 10 -9 meters! Different wavelengths correspond to different colors! Light as a Wave

5. The Doppler Shift Light Waves A B constant wavelength detected by both A and B A detects longer wavelength  redshift B detects shorter wavelength  blueshift Stationary Star AB Star Moving to the Right

6. The Doppler Shift In Astronomy Spectrum of Stationary Source Spectrum of Approaching Source Spectrum of Receding Source 400nm 550nm 700nm

7. A cooler gas in front of a hot dense gas produces an absorption line spectrum - a series of dark spectral lines among the colors of the rainbow.