Our Astronomical Column

Abstract

THE SOLAR ECLIPSE OF 1879, JULY 19.—Though the second of the solar eclipses of next year will not be actually total at any point upon the earth's surface, the difference between the geocentric diameters of sun and moon is sufficiently small to allow of the effect of the augmentation upon the latter, bringing up the phase to one nearly approaching totality in those parts which have the sun close upon the meridian. In the longitude of Aden, or rather, upon the opposite coast of Africa, about Zeyla, the moon's augmented semi-diameter will be only four seconds less than that of the sun, and though the eclipse thus remains annular, it will be seen that the annulus is very narrow in this part of its path—including its passage across Abyssinia. At Aden, there will be a very large eclipse, beginning at 10h. 23m. A.M., local mean time, and ending at 2b. 1m. P.M.; at greatest phase about 0h. 12m., the magnitude will be 0.97 of the sun's diameter. The difference between the illumination of the sky while any portion, no matter how small, of the direct light of the sun remains, and the instant it is entirely extinguished in a total eclipse, is so great as we know from our experience of total eclipses, that there may probably be a doubt as to the possibility of utilising the eclipse in question, in a further endeavour to observe the intra-mercurial planet or planets discovered by Prof. Watson. The next total eclipse of the sun will take place on January 11, 1880, and although, notwithstanding the long track of the shadow across the Pacific Ocean, it may be possible to secure observations, the interval available for so doing cannot be more than half that at the command of observers during the eclipse which traversed the United States last July.