Gauss's law for gravity provides an alternative formulation to Newton's law of universal gravitation. It states that the integral of the gravitational field g dotted with the outward surface normal over any closed surface S equals -4πG times the mass enclosed by the surface. This law allows easy calculation of g due to symmetrical mass distributions like a point mass, spherical mass, line mass, or planar mass by choosing an appropriate Gaussian surface and evaluating the surface integral. For a point mass, choosing a spherical surface yields the familiar inverse square relationship for g.