Having neared the major axis of our elliptical orbit at perihelion, has there been zero offset from all previous orbits for 4.6 billion years? Thus the same orbit and invariant period? A perfect chronometer i.e. perfect accuracy? Better than pulsars or atomic clocks?
That is, essentially no change in mass for our stellar system; thus no change in curvature. However if we reside in a sea of gravity waves, or if one gravity wave rolled through our stellar system, changing curvature, then would not the orbital arc length change, hence affecting the orbital period? Hence no longer a perfect chronometer?