Equivalence Principle for Massive Bodies. I. Phenomenology

The experimentally measured equality of inertial mass (mᵢ) and gravitational mass (mg) of a body indicates nothing about the mgmᵢ ratio to the order of gravitational self-energy/total energy of the body. Experiments are discussed, using astronomical bodies, which measure mgmᵢ to the order of the gravitational self-energy of the bodies. The configuration of the stable three-body problem of Lagrange is shown to be particularly sensitive to the possible difference Δ≡mgmᵢ-1 of the Sun.