Earth's precession of its orbit inclination (i) and ascending node (Omega) over the last ten million years, a result of the planets' gravitational pulls on each other. It helps produce the "Milankovitch cycles" of the Earth's sunlight inputs, which are involved in the comings and goings of the Ice-Age continental glaciers. The center + is for the invariable plane. Referred to present (J2000) equinox and ecliptic. Calculated from the quasiperiodic-series approximations in J. Laskar, "Secular evolution of the Solar System over 10 million years", Astronomy and Astrophysics, 198, 341-362 (1988). http://adsabs.harvard.edu/abs/1988A&A...198..341L