I did one minute of research on changing the mass of a planet, and I was shown to be wrong. Thank you, Straight Dope.
(3) Orbital instability. This has been the most controversial area of all. At first my reaction was, what orbital instability? Everybody knows that the radius of the earth's orbit r = GM/v2, where G is the gravitational constant, M is the mass of the sun, and v is the earth's orbital velocity. In other words, orbital radius is independent of planetary mass, so despite the loss of 1/81 of the combined terralunar bulk, orbitwise the earth would rock on. Various individuals claim, though, that earth's orbit would become more elliptical, its axial tilt would become wobblier due to the influence of Jupiter, and who knows what else. If God had been subject to this kind of environmental impact stuff, the creation of the universe would still be in community hearings. I say let her blow. How bad could it be?
My old physics teacher would shake his head at my mistake. Well, that's why I don't write hard SF.