Hello, after much thought I decided to ask here about the specifics of 2 of the effects of G.R., which are a bit unclear to me. The scenario is - one pulsar and one neutron star orbiting their barycenter as you can see from the image below (ignore the binary pulsar title of image, it's just what I have found on web). One of the effects of G.R. is that the pulsar's (right orbit) periastron will change over time. The change was measured at 4 degrees each year. It's the same as Mercury with it's change of 43 arc seconds every 100 years of it's perihelion. Why exactly is that? It's due to the perturbations caused by neutron star on the pulsar's orbit ? Or in case of Mercury, of the other outer planets perturbing it's orbit? I know for Mercury that the Schwarzschild radius/ Mercury-Sun radius is the smallest for the entire solar system, that's why we can see this effect at it's best. It has something to do with ripples in space-time sent outward at c by the Sun and perturbing Mercury's orbit? I would like a link with some in-detail explanation of this effect if it's possible. Now for the second effect: gravitational redshift. I understand this effect pretty well, but in this scenario (neutron-pulsar system) we are talking about pulsation periods. The change in pulsations can be seen from the formula was ΔPp/ P = [ 1+(Vr/c)/ 1-(Vr/c)]-1/2 – 1, Vr being the radial velocity. Now for the actual question: When both objects are at their periastron (so their distance between is at a minimum), the pulsations from the pulsar will be slowed down (from an observer's point of view, which is located outside their gravitational fields). Why is that? Is it because matter pulls time and the presence of the neutron star's gravitational field makes the time go slower from the observer's p.o.v., therefore the pulsations will come at a slower rate from him? Any help is greatly appreciated. Thanks in advance.