Why Does Earth Rotate?

The equation of time (EoT) tracks daily deviations in length between the solar day and the mean day. Since the length of the mean day remains constant throughout the year, the EoT must mirror daily fluctuations in the length of the solar day. Furthermore, if the Sun meridian declination (SMD) is dynamically linked to Earth’s rotational speed (ERS) the EoT must obey to oscillations in ERS. This document examines the position, velocity, acceleration, and net drive of the mean-time Sun within a solar sundial noon analemma considering both its vertical and horizontal dimensions: the SMD and the EoT. Evidence supports that ERS decreases monotonically along two trans-equinoctial analemmatic phases in which the net drives of the EoT and SMD become coordi-nated (either both accelerating or both decelerating) within the SMD interval of −16 to +19 arcdeg, centered at +3. Conversely, ERS increases monotonically along two trans-solstitial analemmatic phases in which the net drives of the EoT and SMD become opposed, outside the specified interval of SMD. The ERS reaches its minima and maxima at the troughs and crests of the EoT.