  We report the discovery of a statistically significant radial alignment of
cluster galaxies in a sample of 85 X-ray selected clusters observed in the
Sloan Digital Sky Survey. The tendency for alignment is a robust feature of our
sample and does not vary significantly with individual cluster or galaxy
properties. We use dynamical arguments to show that a significant fraction of
cluster galaxies should be undergoing a parametric tidal resonance that can
cause their long axes to orient themselves towards the center of the cluster
potential, and therefore tentatively ascribe the observed radial alignment to
this dynamical effect.
