THE LUNAR APPULSE OF 1937 MAY 25

Abstract

The circumstances of the penumbral lunar eclipse of 1937 May 25 are listed in Table I and are illustrated by the diagram reproduced in Figure 1 ; they were derived, by a semi-graphic method, from the ephemerides of the Sun and of the Moon given in the nautical almanacs ; the semidiameters of the physical umbra and penumbra were obtained by adding two per cent to the semidiameters of the geometrical umbra and penumbra, respectively; the negative magnitude of the penumbral eclipse represents the closest approach of the Moon's limb to the physical umbra, the diameter of the Moon being the unit ; the moments when the Moon enters' and leaves the penumbra are, of course, unobservable ; the immersion of the northern limb of the Moon into the inner, optically effective layers of the penumbral cone will be of short duration.