New members of the group are very often found. The number of asteroids now known amounts to about three hundred and twenty. Ceres is estimated by Professor Barnard, of the Yerkes Observatory, Chicago University, to be six hundred miles in diameter. Vesta is about two hundred and fifty miles in diameter. Meta, on the other hand, is less than seventy-five miles. There are some smaller ones that do not measure twenty miles in diameter, and it is probable that there are many which are so small as to be absolutely invisible to the best telescopes, and which measure only a few hundred rods in diameter. Twenty thousand Vestas would be needed to make one globe equal to our earth in size. Are they _worlds_? Why not? Is not a drop of water, shown in the microscope, peopled with a multitude of various beings? Does not a stone in a meadow hide a world of swarming insects? Is not the leaf of a plant a world for the species which inhabit and prey upon it? Doubtless among the multitude of small planets there are those which must remain desert and sterile, because the conditions of life (of any kind) are not found united. But we can not doubt that on the majority the ever-active forces of nature have produced, as in our world, creations appropriate to these minute planets. Let us repeat, moreover, that for nature there is neither great nor little. And there is no necessity to flatter ourselves with a supreme disdain for these little worlds; for in reality the inhabitants of Jupiter would have more right to despise us than we have to despise Vesta, Ceres, Pallas, or Juno. The disparity is greater between Jupiter and the earth than between the earth and these planets. A world of two, three, or four hundred miles in diameter is still a continent worthy to satisfy the ambition of a Xerxes or a Tamerlane. CHAPTER V. THE LEADING MEMBERS OF OUR FAMILY--SECOND GROUP. Leaving behind us the busy zone of planetoids, hurrying round and round the sun in company, we cross a wide gap, and come upon a very different sight. The distance from the sun which we have now reached is little less than four hundred and fifty millions of miles, or about five times as much as the earth’s distance; and the sun in the heavens shows a diameter only one-fifth of that which we are accustomed to see. Slowly--yet not slowly--floating onwards through space, in his far-off orbit, we find the magnificent planet Jupiter.