No. 37: Jan-Feb 1985
Many radio galaxies and quasars are found to have a double-lobed structure, with one lobe on one side of the nucleus and another diametrically opposite. When examined in detail, these lobes turn out to be quite different in size, shape, and intensity. In particular, very bright regions on one lobe often correspond to gaps or regions of low brightness on the other. So striking are these asymmetries that astronomers think that these huge, tremendously energetic systems are ejecting material first from one side then the other. Somehow, one side of the galaxy or quasar communicates with the other, which may be many light years away, and coordinates a flip-flop action. How and why radio galaxies and quasars should flip-flop is a major mystery.
(Anonymous; "Flip-Flop Radio Jets?" Sky and Telescope, 68:506, 1984.)
Comment. This flip-flop action immediately recalls the great elliptical galaxies which seem to be shooting out shells of stars first from one end, then the other.