Planet X is observed to have a small moon. This moon is observed to orbit the planet once per month at a distance of 15 Planet X diameters. What is the mass of Planet X in solar masses? [Hint: Use Newton's form of Kepler's Third Law: P2 is proportional to a3/M, where M is the mass of Planet X (assuming that the mass of the moon is negligible in comparison).] the diameter of planet X is .0008 au as derived from previous problems. so 15 planet x diameters would be .012 So this would be a correct? And p would be 30 days? so the mass would be M = .012^3/30^2? If this is correct am i missing something because i cannot come up with the correct anwer.