Fig. 67.—Woman's head in the Moon.
From the earliest astronomical observations made with the aid of instruments by Galileo, in 1609, people tried to find out what the dark spots could represent, and they were called seas, because water absorbs light, and reflects it less than terra firma. The Moon of itself possesses no intrinsic light, any more than our planet, and only shines by the light of the Sun that illuminates it. As it rotates round the Earth, and constantly changes its position with respect to the Sun, we see more or less of its illuminated hemisphere, and the result is the phases that every one knows so well.
Fig. 68.—The kiss in the Moon.
Fig. 69.—Photograph of the Moon.
At the commencement of each lunation, the Moon is between the Sun and the Earth, and its non-illuminated hemisphere is turned toward us. This is the New Moon, invisible to us; but two days later, the slim crescent of Diana sheds a gentle radiance upon the Earth. Gradually the crescent enlarges. When the Moon arrives at right angles with ourselves and with the Sun, half the illuminated hemisphere is presented to us. This is the first quarter. At the time of Full Moon, it is opposite the Sun, and we see the whole of the hemisphere illuminated. Then comes the decline: the brilliant disk is slightly corroded at first; it diminishes from day to day, and about a week before the New Moon our fair friend only shows her profile before she once more passes in front of the Sun: this is the last quarter.
