We demonstrate that the motion of the solar system barycentre can be reconstructed directly from planetary ephemerides using mass-weighted superposition, without numerical integration or force evaluation. Using JPL Horizons data in the Solar System Barycentre (SSB) frame, the reconstructed solar motion agrees with the reference solution to within ≈242 km RMS and reproduces radial velocity variations at the ≈0.009 m s−1 level. As an external validation, Pluto (excluded from the reconstruction) is recovered in the SSB frame with comparable accuracy and no secular drift. These results indicate that planetary motion is strongly constrained by global barycentric structure and phase coherence. The method provides a simple and stable framework for analysing gravitational dynamics in multi-body systems.
Rafferty et al. (2026) studied this question.