The story of the sun, moon, and stars . back, either by the solarheat, by the light, by electricity, or by other forces;and this extension is rather a motion in the ether thana real transport of matter, at least in the great comets 254 STORY. OF THE SUN, MOON, AND STARS. which approach very near the sun, and in their im-mense luminous appendages. The effects producedand observedare not the same in all comets, which GREAT COMET OF 1744. proves that they differ from each other in several re-spects. The tails have sometimes been seen to di-minish before the perihelion passage, as in 1835, MORE AB
The story of the sun, moon, and stars . back, either by the solarheat, by the light, by electricity, or by other forces;and this extension is rather a motion in the ether thana real transport of matter, at least in the great comets 254 STORY. OF THE SUN, MOON, AND STARS. which approach very near the sun, and in their im-mense luminous appendages. The effects producedand observedare not the same in all comets, which GREAT COMET OF 1744. proves that they differ from each other in several re-spects. The tails have sometimes been seen to di-minish before the perihelion passage, as in 1835, MORE ABOUT COMETS AND METEORITES. 255 Luminous envelopes have also been seen succeedingeach other round the head, concentrating themselveson the side opposite to the sun, and leaving the cen-tral line of the tail darker than the two sides. Thisis what happened in the Donati comet and in that of1861. Sometimes a secondary tail has been seen pro-jected towards the sun, as in 1824, 1850, 1851, and1880. Comets have been seen with the head envel-. THE FIRST COMET OF 1888—JUNE 4. oped in phosphorescence, surrounding them with asort of luminous atmosphere. Comets have also beenseen with three, four, five, and six tails, like that of1744, for example, which appeared like a splendidaurora borealis rising majestically in the sky, until,the celestial fan being raised to its full height, it wasperceived that the six jets of light all proceeded fromthe same point, which was nothing else but the nu-cleus of a comet. On the other hand, the nucleithemselves show great variations—some appear sim-ply nebulous, and permit the faintest stars to be vis- 256 STORY OF TH£ SUN, MOON, AND STARS. ible through, them; others seem to be formed of oneor more solid masses surrounded by an enormous at-mosphere; in others, again, a nucleus does not exist,as in the Southern comet of 1887. One of the cometsof 1888 showed a triple nucleus and a bristling coma,as may be seen in the cut. We may, then, considerthat th
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Keywords: ., bookcentury1800, bookdecade1890, bookidstor, booksubjectastronomy
