The Sun revolves around the center of the Milky Way Galaxy (Fig. 5–49) at a distance of about 30,000 light-years from the center (1 ly = 9.5 × 1015 m). If it takes about 200 mil- lion years to make one revolution, 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 (2 × 1030 kg), how many stars would there be in our Galaxy? Sun - 30,000 ly- FIGURE 5-49 Edge-on view of our galaxy. Problem 84.

The Sun revolves around the center of the Milky Way Galaxy (Fig. 5–49) at a distance of about 30,000 light-years from the center (1 ly = 9.5 × 1015 m). If it takes about 200 mil- lion years to make one revolution, 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 (2 × 1030 kg), how many stars would there be in our Galaxy? Sun - 30,000 ly- FIGURE 5-49 Edge-on view of our galaxy. Problem 84.