And, as he sinks below the shading earth,
With awful train projected o’er the heavens,
The guilty nations tremble.”
Even Napoleon I. had servile flatterers who, as late as 1808, tried to extract astrological influence out of a comet by way of bolstering up “Old Bony.” But enough of poetry and fiction, let us hasten back to prosaic fact.
Fig. 19.—Telescope Comet with a nucleus.
Comets as objects to look at may be classed under three forms, though the same comet may undergo such changes as will at different epochs in its career cause it to put on each variety of form in succession. Thus the comet of 1825 seen during that year as a brilliant naked-eye object, after being lost in the sun’s rays, was again found on April 2, 1826 by Pons. Lamentable were his cries at the miserable plight it was in. He described it as totally destroyed: without tail, beard, coma or nucleus, a mere spectre. The simplest form of comet is a mere nebulous mass, almost always circular, or perhaps a little oval, in outline. It may maintain this appearance throughout its visibility; or, growing brighter may become a comet of the second class, with a central condensation, which developing becomes a “nucleus” or head. It may retain this feature for the rest of its career, or may pass into the third class and throw out a “coma” or beard, which will perhaps develop into a tail or tails. Doing this it will not unfrequently grow bright enough and large enough to become visible to the naked eye. In exceptional cases the nucleus will become as bright as a 2nd or even 1st magnitude star, and the tail may acquire a length of several or many degrees. In the last named case of all the comet becomes, par excellence according to the popular sentiment, “a comet.” It will now be readily inferred that the astronomer in his observatory has to do with many comets which the public at large never hear of, or if they do hear of, treat with contempt, because they are destitute of tails.
Fig. 20.—Wells’s Comet of 1882, seen in full daylight near the Sun on Sept. 18.
