The sun, which is 2.2 × 1020 m from the center of the milky way galaxy, revolves around that center once every 2.5 × 108 years. assuming each star in the galaxy has a mass equal to the sun’s mass of 2.0 × 1030 the stars are distributed uniformly in a sphere about the galactic center, and the sun is at the edge of that sphere, estimate the number of stars in the galaxy. note: the actual number of stars in the milky way is between 1011 and 4 × 1011 .