Ceres, the first-found asteroid, is so small that one hundred and twenty-five thousand little worlds of its size could be made out of our own world. Fifty little globes like Ceres, set side by side, would form a line as long as the diameter of our world. As the mass of Ceres is so much less than that of our world, the attraction of gravity is less--anything is fifty times as heavy on our world as it would be on Ceres. So if a boy could live on Ceres, and have as much muscular force as he has here, he could play easily with a ball that here weighs a quarter of a ton. A baby on Ceres could tumble about a cannon-ball as easily as a baby here plays with a rubber ball. If a house fell over on a man, he could set it up as easily as here he could set up a fallen peach-basket. Of course it is only a play of fancy that there are men, boys, or babies on Ceres. Perhaps there is no living thing there. If there are living creatures, all their habits and ways of life must be very different from ours. But if people from our earth could go to Ceres, why would they find such wonderful differences there in weights, and in the effect of an output of strength? We have seen that Ceres is very much smaller than our earth; its mass is greatly less, and just in proportion to the smallness of its mass is the force of the pull it exerts over objects, or the attraction of gravitation; this attraction is dependent upon the mass of the body exercising it, and upon the distance of the body attracted. When the distance between two bodies is great the attraction is weaker, and when a body is small its attracting power is less in proportion. Ceres is such a small planet that its pull over objects is small. Similarly, we might say of the planet Mars that its mass is so small, as compared with that of the earth, that a body which on the earth would weigh one hundred pounds would weigh much less on Mars; and where you could jump up five feet here, you could rise many feet there. The best athlete who can make a jump here, can rise only a few feet into the air; then down he comes, pulled by the force of gravity, the attraction of the earth. But on Ceres attraction is so small an affair that a man could jump over a dome as high as St. Peter’s or St. Paul’s without creating any excitement. In fact, on Ceres a man would weigh only one-fiftieth part what he weighs here, and the same output of muscular activity as is used here would have a fifty-fold value. Much the same conditions exist on the other asteroids. When first discovered it was supposed that the asteroids were fragments of some very large planet which had gone to pieces. That theory has been disproved, and now the nebular hypothesis of Laplace is generally admitted to account satisfactorily for these little planets.