The story of the sun, moon, and stars . soning thus about the comets, as we watchthem from our earth-boat in the ocean of space, wefeel little doubt that for each one which we can see,millions pass to and fro beyond reach of our , so long ago as the days of Kepler, that greatastronomer gave it as his belief that the comets inthe Solar System, large and small, were as plentifulas the fishes in the sea. And all that modern as-tronomers can discover only tends to strengthen thisview. Why should the comets be called visitors? Icall them so simply because many of them are
The story of the sun, moon, and stars . soning thus about the comets, as we watchthem from our earth-boat in the ocean of space, wefeel little doubt that for each one which we can see,millions pass to and fro beyond reach of our , so long ago as the days of Kepler, that greatastronomer gave it as his belief that the comets inthe Solar System, large and small, were as plentifulas the fishes in the sea. And all that modern as-tronomers can discover only tends to strengthen thisview. Why should the comets be called visitors? Icall them so simply because many of them are , it is true, belong to the Solar System. But 76 STORY OF THE SUN, MOON, AND STARS. even in their case, strong donbts are felt whether theywere not once visitors from a distance, caught in thefirst instance by the attraction of one of the largerplanets, and retained thenceforward, for a time at least,by the strong attraction of the sun. Every comet, like every planet, has his own orbitor pathway in the heavens, though the kind of orbit. PASSAGE OF THE EARTH AND THE MOON THROUGH THE TAII, OF A COMET. varies with different comets. There are, first, thosecomets which travel round and round the sun inclosed orbits—that is, in a ring with joined the ring is always oval, not round. There are,secondly, those which travel in an orbit which may beclosed; but if so, the oval is so long and narrow, andthe farther closed end is at so great a distance, thatwe can not speak certainly. There are, thirdly, thosewhich decidedly are mere visitors. They come fromthe far-off star-depths, flash once with their brillianttrains of light through our busy Solar System, causing VISITORS. J7 some little excitement by the way, and go off in an-other direction, never to return. Only a small part of the orbits of these comets canbe seen from earth; but by careful attention astrono-mers learn something of the shape of the curve inwhich they travel. It is in that way possible to cal-culate, someti
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Keywords: ., bookcentury1800, bookdecade1890, bookidstor, booksubjectastronomy
