Asteroids

Aiton's Encyclopedia (1910)

small planets traveling between Mars and Jupiter. Kepler, and after him others, suggested that a planet might naturally be looked for in the wide gap between Mars and Jupiter. The discovery of Uranus in a similar gap led to the formation of an association of twenty-four astronomers who subdivided the zone in question and began a careful search for the expected planet. January 1, 1801, an Italian astronomer, Piazzi, discovered a very small planet which he called Ceres. A little over a year later Pallas was found in the same locality. Two years later Juno, and three years later again, Vesta were discovered. So many have been found since, that Grecian mythology has been pretty well ransacked for names, and a circle with an inclosed figure is now the astronomer's nomenclature. The number of asteroids has passed five hundred. In place, then, of the expected planet, a host of fragments have been found, as though a world had exploded; but we may add that the paths of these little planets have no point of intersection such as might have been expected had they originated in the break-up of a large body. The bulk of the asteroids all put together is less than that of the moon. They range from ten to one hundred miles in diameter. They are so small and their attraction of gravitation so slight that it is thought that a pebble flung with very ordinary force from any one of them would never fall to the surface again. Professor Young states that the orbits of the asteroids so cross and interlink that, if they were material hoops or rings, the lifting of one would take all the others with it.