Our Astronomical Column

Abstract

MARS IN 1894.—Sienor G. Schiaparelli remarks, in No. 3271 of the Astronomische Nachrichten, that the unfavourable state of the atmosphere during the opposition of Mars last year rendered magnifications beyond 200 impossible except in rare instances. Speaking generally, he says that the “seas” were less pronounced than in 1877, and the “canals” were better visible in 1894, and seen in greater numbers. Some of the largest ones showed faint traces of doubling, but, with the magnifying powers used, nothing could be made out with certainty on this point. The southern pole cap became invisible in the 18-inch Milan refractor at the end of October. On October 8 it had already become very faint. The total disappearance cannot have been later than October 29, i.e. on the 59th day after the southern solstice of the planet. This is unusually early. In 1877-78 it was well seen as late as 98 days after the solstice. In the present case it is pretty certain that the whole of the southern pole cap was melted. A great change was also observed in the isthmus or peninsula of Hesperia, which separates the Mare Tyrrhenum from the Mare Cimmerium. It was apparently separated into two unequal portions by a newly formed-channel. The Mare Sirenum, which in October, 1892, had been separated into two parts, was in October, 1894, seen to have resumed its ordinary aspect. But on November 21 the separation had reappeared. “This fact,” says Schiaparelli, “and other analogous ones which I have observed in previous oppositions, lead to the conclusion that the abnormal changes in the markings of Mars do not take place by chance and without regularity, but that the same variation may reappear, with the same aspect, even after a long interval of time. The form and extent of such changes is determined by some element which is stable, or at least periodic.”