Possible Origin of Some Periodicities Detected in Solar-Terrestrial Studies: Earth's Orbital Movements

Periodicities matching planetary cycles have been argued to be detected in key geophysical time series. In general, these periodicities were indirectly attributed to a planetary influence on solar activity. This supposes that planetary gravity affects the internal functioning of the Sun's dynamo, that is, the planetary hypothesis (PH) of the solar cycles. The Earth's heliocentric dynamics already includes the planetary gravitational effects on the Sun. Taking into account this fact, these periodicities, ultimately attributed to possible planetary modulations of the solar activity, could have a more direct origin in cyclical changes in the relative Sun-Earth geometry, but then, wrongly or partially explained invoking internal solar changes. We present an original decomposition analysis of the high-precision ephemeris DE431 from NASA/JPL in order to obtain and classify the most important planetary/lunar purely periodic changes of the Earth's orbital movement at sub-Milanković scales. A comprehensive list of cyclic changes of the Earth's orbital parameters involved in the relative Sun-Earth position and the Earth's speed around the Sun is given. We show that these particular geophysical quasi-periods are identifiable in the cyclic oscillations of these orbital parameters. Since the Earth's movement in space physically affects the manner in which the solar radiant flux reaches the planet, these oscillations provide, unlike the PH, a clear, causal, and testable link for their possible attribution.