If the Earth stayed in one place and just rotated on an upright axis* then all days would have the same length. When we look at the Sun we are observing it from a moving platform. It is the varying speed around its elliptical orbit and the tilted axis which are responsible for the daily variations accounted for by the Equation of Time.
· *Impossible of course as it is the orbital motion which prevents the Earth being dragged inwards by the Sun’s gravity.
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