The ratio of the mass of the earth to the mass of the moon is 81.0. Assume that the radius of the earth is about 6481.0 km and that the distance between the center of the earth and the moon is 385126.0 km.
The earth-moon system moves in a circular orbit around the sun. How far from the circular orbit does the center of the earth move radially (i.e. toward or away from the sun) during the lunar month?
Determine the distance of the center of mass of the earth-moon system from the center of the earth is = 4696.7 km but when I tried multiplying it by 2 for the question above, it was incorrect.