Page:A princess of Mars.djvu/69

I ELUDE MY WATCH DOG nights are either brilliantly illumined or very dark, for if neither of the two moons of Mars happen to be in the sky almost total darkness results, since the lack of atmosphere, or, rather, the very thin atmosphere, fails to diffuse the starlight to any great extent; on the other hand, if both of the moons are in the heavens at night the surface of the ground is brightly illuminated.

Both of Mars' moons are vastly nearer her than is our moon to Earth; the nearer moon being but about five thousand miles distant, while the further is but little more than fourteen thousand miles away, against the nearly one-quarter million miles which separate us from our moon. The nearer moon of Mars makes a complete revolution around the planet in a little over seven and one-half hours, so that she may be seen hurtling through the sky like some huge meteor two or three times each night, revealing all her phases during each transit of the heavens.

The further moon revolves about Mars in something over thirty and one-quarter hours, and with her sister satellite makes a nocturnal Martian scene one of splendid and weird grandeur. And it is well that nature has so graciously and abundantly lighted the Martian night, for the green men of [49]