Page:Astronomy for Everybody.djvu/219

it is supposed that the ring forming the minor planets did not collect in this way, but separated into innumerable fragments.

There is a curious feature of the orbits of these bodies which may throw some light on the question of their origin. I have explained that the planetary orbits are nearly exact circles, but that these circles are not centred on the sun. Now imagine ourselves to look down upon the solar system from an immense height, and suppose that the orbits of the minor planets were visible as finely drawn circles.
Fig. 35.—Separation of the Minor Planets into Groups. These circles would appear to interlace and cross each other like an intricate network, filling a broad ring of which the outer diameter would be nearly or quite double the inner one.

But suppose we could pick all these circles up, as if they were made of wire, and centre them all on the sun, without changing their size. The diameters of the larger ones would be double those of the smaller, so that the circles would fill a broad space, as shown in the figure. Now, the curious fact is