1. Redshift Hubble’s Law

2. Redshift - absorption spectra

3. Plot of intensity

5. From doppler effect From triangulation of movement of Earth

6. Increase in distance over time A B C

7. 3 Galaxies A,B & C A B C

8. After time t A B C

9. A B C A B C Distance travelled

11. = H 0 d where Ho = 2·4 × 10 −18 s −1

13. 1Parsec = 3.262 light years

15. Edwin Hubble

16. Three astrophysicists are discussing the results of observations that show that all stars have their light frequencies decreased by a small amount – ‘red shift’ Professor Bubble “The red shift shows the stars are all moving away from our stationary Solar System” Doctor Toil “The red shift shows that we are moving away from the rest of the universe at high speed” Professor Trouble “The red shift shows the stars are moving away from each other”

17. Which viewpoint do you agree with and why? Why do you disagree with the other two or do you think no one is correct? What additional data from observations of starlight would allow confirmation? Professor Bubble “The red shift shows the stars are all moving away from our stationary Solar System” Doctor Toil “The red shift shows that we are moving away from the rest of the universe at high speed” Professor Trouble “The red shift shows the stars are moving away from each other”