1. Chapter 16: Hubble’s Law and Dark Matter 3C295 in X-rays 5 billion light years away and 2 million light years across.

2. Chapter 16: Hubble’s Law and Dark Matter Hubble began to determine distances and red shifts of galaxies.

3. Chapter 16: Hubble’s Law and Dark Matter He discovered there was a linear relationship between distance and velocity. The relationship is now called Hubble’s Law.

4. Chapter 16: Hubble’s Law and Dark Matter We now have techniques that we can use to determine distance out to the visible edge of the Universe.

5. Chapter 16: Hubble’s Law and Dark Matter But as we watch the movements of clusters of galaxies we discover they move faster than the gravity of the visible matter would predict. The galaxies have cluster rotation curves that also hint at “Dark” matter.

6. Chapter 16: Hubble’s Law and Dark Matter Huge surveys of galaxies so patterns of clumping which again point to more gravity than the visible matter would predict.

7. Chapter 16: Hubble’s Law and Dark Matter Large chains and voids are formed.

8. Chapter 16: Hubble’s Law and Dark Matter Gravitational lenses produce rings and arcs which can be used to explore the gravitational field around distant galaxies.

9. Chapter 16: Hubble’s Law and Dark Matter

10. Evolution of galaxies.