# CQW holiday project: gravitational field of a cube

29 Jul 2015show that the lowest two non-vanishing multipole components of the gravitational field of a cubical planet are the monopole and the octupole. what’s the next-lowest non-vanishing multipole? (a solution without a multipole expansion and the added bonus question on the shape of the surface of a lake on such a planet is discussed in the paper “the gravitational field of a cube” by J.M. Chappell, A. Iqbal, D. Abbott and M. Chappell.)