Our Astronomical Column

Abstract

AN ANCIENT “URANOMETRIA.”—We have received a very interesting work, published by Dr. Schjellerup, of the Observatory of Copenhagen, under the auspices of the Imperial Academy of Sciences of St. Petersburg. It contains a description of the constellations, with the star magnitudes, composed in the middle of the tenth century by the Persian astronomer, Abd-al-Rahman al-Sûfi, and is a literal translation of two Arabic manuscripts preserved in the Royal and Imperial libraries of Copenhagen and St. Petersburg. A more particular account of the valuable addition which Dr. Schjellerup has made to the literature of astronomy will be given in this column next week. Meanwhile, we may just note one curious statement made by the Persian astronomer with reference to the well-known variable star Algol, viz., that at the time of his observations the star was reddish—a characteristic applied also to Antares, Aldebaran, a Hydræ, and a few other stars, which are also reddish in our own day; but at present there is no tinge of colour about Algol, which may be fairly described as a white star, and if there be one of its class more than another in which the periodical fluctuation of light can with much appearance of probability be attributed to the intervention of a revolving attendant; passing regularly in our line of sight, it is to this star that we might point in illustration. Its former ruddy light, however, rather necessitates a different explanation, and one which, notwithstanding the comparative regularity of its changes, may perhaps assimilate it to the more numerous class of variable stars.