Page:The evolution of worlds - Lowell.djvu/131

Rh With regard now to their more individual characteristics, the asteroids may be said to agree in one point—their diversity, not only to all the larger members of the solar family, but to one another. For they travel in orbits ranging in ellipticity all the way from such as nearly approach circles to ellipses of cometary eccentricity. They voyage, too, without regard to the dynamical plane of the system, or, what is close to it, the ecliptic; departing from the general level often 30° and, in one instance, that of the little planet dubbed W. D., by as much as 48°. This eccentricity and inclination put them in a class by themselves. It is associated and unquestionably connected mechanically with another trait which like-wise distinguishes them from the planets more particularly—called their diminutive size. Only four—Vesta, Ceres, Pallas, and Juno—out of the six hundred odd now known exceed a hundred miles in diameter, and the greater number are hardly over ten or twenty miles across. Very tiny worlds indeed they would seem, could we get near enough to them to discern their forms and features. Curiously enough, reasoning on certain light changes they exhibit has enabled us to divine something of their shapes, and even character. Thus it was soon perceived that Eros fluctuated in the light he sent us, being at times much brighter than at others. In February and March, 1901, the changes were such that their maximum exceeded three times their minimum two