Baily's Beads

Baily's Beads, the name given to a phenomenon in connection with eclipses of the sun, first fully described by Francis Baily. Just before the beginning and after the end of the obscuration by the moon of the sun's disc, the thin crescent-shaped unobscured portion of the sun seems usually to become suddenly discontinuous, and looks like a belt of bright points, varying in size and separated by dark spaces. The resulting appearance has been compared to a string of beads. The phenomenon is an effect of irradiation and the inequalities of the moon's edge. To irradiation it is also due that, by defect of the retina of the eye, bright objects seen on a dark ground seem larger than they really are.