We have augmented a Michelson-Morley interferometer with additional instrumentation and secured additional measurements of a type not previously reported by other researchers. Where the original Michelson-Morley experiment looked only at the interference between two beams that had traversed the two interferometer arms, we look at the standing-wave interference within one of the arms as well. Assuming that the interferometer is resident in an inertial coordinate frame, special relativity theory predicts nodes spaced /2 apart. Our experiment shows a departure from this expected nodal spacing. The discrepancy is here shown to be consistent with an anisotropy in the speed of light having the form c(
) = c/[1+(v0/c) cos () ], where c is the usual 3 ? 108 m/s, v0 is about 378 km/s, and = 0 lies in a unique direction relative to fixed stars. The apparent v0 is consistent with both the known anisotropy of background cosmic radiation and the believed orbital velocity of the Sun in the Milky Way Galaxy.
