Why does the moon orbit earth? a. the moon is less dense than earth. b. the mass of earth is much greater than the moon. c. the moon came into orbit around earth after earth was established. d. the velocity of the moon in orbit is faster than the velocity of earth in orbit around the sun. a. about 41.4 trillion n b. about 42.5 trillion n c. about 65.2 trillion n d. about 74.0 trillion n