The period of moon around the earth is 28 days and radius of its orbit is 4×10^5 km. Find the mass of earth. Share with your friends Share 1 Ved Prakash Lakhera answered this The formula of period of moon around the earth is, T = 2πR+x3GMOR M = 4π2R+x3GT2.We are given T= 28×24×3600 s, R+x=4×108m and G= 6.67×10-11Nm2/Kg2, so M = 4×3.14×3.14×64×10246.67×10-11×28×24×3600×28×24×3600 M=6.46×1024Kg. 4 View Full Answer