INDICATION OF LUMINESCENCE FOUND IN THE DECEMBER 1964 LUNAR ECLIPSE

Abstract

There is considerable evidence that some areas of the lunar surface fluoresce as a result of unimpaired bombardment by shortwavelength and corpuscular solar radiation. Dubois1'2 and Kozyrev3 sought the effect that this luminescence would have upon the depths and profiles of the Fraunhofer lines in the lunar spectrum. Both obtained some positive results. Dubois found that the light contribution of the luminescence was generally greater on the maria than on the continents and that in any given region it varied appreciably with time.2 He obtained contributions ranging as high as 25 percent. Another possible manifestation of this luminescence appears during lunar eclipses, when it is often observed that the moon's brightness within the innermost part of the penumbra is greater than expected from theoretical considerations. Link studied 16 recent eclipses for which reliable photometric data were available and found that 12 exhibited this excess.4 He suggested that this excess be interpreted as luminescence, which becomes observationally more prominent during the inner penumbral phase because the corona (assumed to be the primary source of the exciting radiation) is actually out of eclipse at that time. He concluded that about 10 percent of the moon's optical radiation is caused by luminescence.