1. The problem statement, all variables and given/known data The sun rotates around the center of the Milky Way Galaxy at a distance of about 30,000 light-years from the center (1 light year=9.5x10^15 meters). If it takes about 200 million years to make one rotation, estimate the mass of our Galaxy. Assume that the mass distribution of our Galaxy is concentrated mostly in a central uniform sphere. If all the stars had about the mass of our sun (2x10^30 kg), how many stars would there be in our Galaxy? 2. Relevant equations 3. The attempt at a solution For the mass of the Galaxy I got an answer of 3.44425x10^41 kg and I got 1.72213x10^11 stars. I'm pretty sure this isn't right. HELP!?