Page:The Solar System - Six Lectures - Lowell.djvu/91



sight,—the ring system. It baffled Galileo with his opera-glass, who first saw the planet triform, and then, to his surprise, marked the two smaller bodies disappear, as if Saturn had indeed eaten his offspring.

Crowning the planet's equator are several concentric flat rings of light. Three are usually distinguished, known as A, the outer ring ; B, the middle ring ; and C, the inner or dusky ring. The outer, A, has an extreme radius of about 85,700 miles. It is 12,000 miles across, and is separated from B by a dark space 3400 miles wide, known as Cassini's division. B, the broadest and brightest of the rings, is 17,000 miles in width, and is joined without perceptible interval by C, which is much fainter, resembling a crêpe veil stretched from the inner edge of B, 9500 miles toward the planet, from whose limb it is sundered by a gap of between 7000 and 8000 miles.

Two thirds way from the outer to the inner edge of A is another division or dark line, much narrower than Cassini's, and sometimes nearly invisible, known as Encke's division, though suspected before by Short.

Edward Roche, in 1848, was the first to show that the rings were composed of discrete particles,—mere dust and ashes. He drew this