The Sun's Apparent Motion in the Plane of the Ecliptic

  I redid the series of fits for the Sun's apparent position this time in the plane of the Ecliptic. The primary motion is of course a Keplerian ellipse. The horizontal and vertical axes are the major and minor axes and at the beginning of the year the Sun in near perigee on the right and moves upwards. The units are AU.

The Keplerian elements for the fit are as follows.

The residuals of this fit form a rose curve which appears to be due to solar pulls and torques acting on the Moon's orbit. Again the units are AU.

The residuals of the second fit are down to μAUs and more random in appearance. There's an odd step in the direction of increasing perigee at the end of the year. Could the Earth be slowing down and spending more time at perihelion? What effect would that have on global warming?

Fits can produce some deviations when all the error isn't accounted for.