9. In the early 1930's, Fritz Zwicky measured the velocities of galaxies moving within the Coma Cluster. His measurement showed that the galaxies in the Coma Cluster have an average velocity of ~1000 km/s. The visible radius of the Coma Cluster has been measured to be 3 Mpc. (a) Estimate the mass of the Coma Cluster based on this information alone, and be sure to state any assumptions you make. (b) A rough estimate of the total mass of visible matter in the Coma Cluster is 5x 10 2 Mo. What does this mean when comparing the measured total visible mass to that measured by Zwicky? Explain you answer in detail