Equivalence Principle for Massive Bodies. I. Phenomenology

The experimentally measured equality of inertial mass ($m_i$) and gravitational mass ($m_g$) of a body indicates nothing about the $\frac{m_g}{m_i}$ ratio to the order of gravitational self-energy/total energy of the body. Experiments are discussed, using astronomical bodies, which measure $\frac{m_g}{m_i}$ 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 $\Delta \equiv \frac{m_g}{m_i}-1\mathrm{}$ of the Sun.