The 300 year record of the yearly sunspot numbers and numerically generated
trajectory of the solar inertial motion (SIM) were subjects of a synchroni
zation analysis. Phase synchronization of the sunspot cycle and a fast comp
onent of the SIM have been found and confirmed with statistical significanc
e in three epochs (1727-1757, 1802-1832 and 1863-1922) of the entire 1700-1
997 record. This result can be considered as a quantitative support for the
hypothesis that there is a weak interaction of gravity and solar activity.