Abstract
PHYSICAL APPEARANCE OF PERIODIC COMETS.—Comets possess no personal characteristic appearance; hut Mr. Barnard, writing to the Astronomical Journal No. 246, suggests that it may be possible to arrange those of short period according to their physical peculiarities. To the first class he would assign those comets which are large, round, and very gradually brighter in the middle, with no special condensation, and of a very diffused nature. They have no nucleus or tail, and are so decidedly periodic that, trusting to this peculiarity, Mr. Barnard predicted that the comet discovered by Swift in November 1889, and D'Arrest's comet at its return last year, were of short period. The most distinctive members of this class of comets are D'Arrest's, Swift's 1880, Brooks's 1886, and Swift's 1889. There are few nebulæ that resemble this class. A much larger and less exclusive class contain comets which are comparatively small, and which have an indefinite central brightness or nucleus. Many of the parabolic comets resemble these, and there are hundreds of nebulæ exactly like them in telescopic appearance. To this class are assigned comets Faye; Wolf, 1884 III.; Finlay, 1886 VII.; Brooks, 1889 V.; Spitaler, 18go. It is possible that the peculiarities of these two distinct classes of short-period comets may furnish some information as to their relative ages.
Article PDF
Rights and permissions
About this article
Cite this article
Our Astronomical Column. Nature 44, 551 (1891). https://doi.org/10.1038/044551a0
Issue Date:
DOI: https://doi.org/10.1038/044551a0