Abstract
A COMET IN 1717.—In a note to the Royal Society (Phil. Trans., No. 354) Halley reported that on Monday, June 10, 1717, in the evening, the sfcy being very serene and calm, he was desirous of examining Mars, then very near the earth, to ascertain whether in his 20-foot telescope he could distinguish the spot said to be seen upon his disk, and directing his telescope for that purpose he accidentally met with a small whitish appearance near the planet, which seemed to emit from its upper part a short kind of radiation, directed nearly towards the point opposite to the sun. The great light of the moon, then not far from full, and close at hand, hindered the object from being distinctly seen, but he determined its place to be nearly in 17° 12′ of Sagittarius with 4° 12′ south latitude. The position, he adds, would be more exactly found by means of two small stars near it, the more northerly of which had the same latitude and followed at the distance of about six minutes; the other was about four minutes south of the former, and followed it about a minute, “the angle at the northern star was somewhat obtuse, of about 100 degrees, and the distance of the nebula from it was se;quialteral to the distance of the two stars, or rather a little more.” No motion being detected in over one hour, Halley doubted if it were a comet, but on June 15, the moon being down and the sky clear, he had a distinct view of the two stars, but there was no sign of the nebulosity where it had been observed on June 10. He was led by this circumstance to remark upon the number of comets which might escape notice, from their being telescopic objects, and adds that, although comets had been seen elsewhere in 1698, 1699, 1702, and 1707, he could not learn that any comet had been perceived in this country for the thirty-five years previous to the observation above described, which implies that none had been seen here since the year 1682, that of the appearance of the famous comet which bears Halley's name.
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Our Astronomical Column . Nature 31, 419–420 (1885). https://doi.org/10.1038/031419a0
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DOI: https://doi.org/10.1038/031419a0