The
double pulsar PSR J0737 — 3039A / B consists of two neutron stars in a highly relativistic orbit that displays a roughly 30 - second eclipse when pulsar A passes behind pulsar B. Describing this eclipse of pulsar A as due to absorption occurring in the magnetosphere of pulsar B, we successfully used a simple geometric model to characterize the observed changing eclipse morphology and to measure the relativistic
precession of pulsar B's spin axis around the total orbital angular momentum.