The Sun rotates around the center of the Milky Way Galaxy (thefigure below (Figure 1)) at a distance of about 30,000 light-yearsfrom the center (1ly=9.5×1015m). 1.If it takes about 200 millionyears to make one rotation, estimate the mass of our Galaxy. Assumethat the mass distribution of our Galaxy is concentrated mostly ina central uniform sphere. Express your answer using one significantfigure. 2.If all the stars had about the mass of our Sun(2×1030kg), how many stars would there be in our Galaxy? Expressyour answer using one significant figure.
1.
If it takes about 200 million years to make one rotation,estimate the mass of our Galaxy. Assume that the mass distributionof our Galaxy is concentrated mostly in a central uniformsphere.
Express your answer using one significant figure.
2.
If all the stars had about the mass of our Sun (2×1030kg), howmany stars would there be in our Galaxy?
Express your answer using one significant figure.
