The binary pulsar PSR1913+16 is at present the most interesting object for measuring general relativistic effects1 such as the periastron advance, emission of gravitational waves, and gravitational redshift. It also offers unique possibilities for studying the properties of one or two neutron stars. Yet several of the observed effects could be simulated by an extended secondary, and recent optical measurements2,3 have suggested that such is the case, at the 97% confidence level. Here I shall argue that the optical source seen at the position of PSR1913+16 may be the pulsar sphere, that is, a region of confined extremely relativistic plasma glowing in the near IR, and that the secondary is another neutron star (as preferred by most authors). Therefore, the optical coincidence need not cause us to doubt the published general relativistic analysis of this system. I shall also comment on the binary pulsar's likely history, and on the possible presence of a second binary pulsar in Cas A.