1. Certain philosophers hold that the moon has a light of its own, that one part of its globe is bright and another dark, and that turning by degrees it assumes different shapes. Others, on the contrary, assert that the moon has no light of its own, but is illumined by the rays of the sun. And therefore it suffers an eclipse if the shadow of the earth is interposed between itself and the sun.
Chapter 56. On the motion of the moon.
1. The moon governs the times by alternately losing and recovering its light. It advances like the sun in an oblique, and not a vertical course, for this reason, that it may not be opposite the center of the earth and often suffer eclipse. For its orbit is near the earth. The waxing moon has its horns looking east; the waning, west; rightly, because it is going to set and lose its light.
Chapter 57. On the nearness of the moon to the earth.
1. The moon is nearer the earth than is the sun. Therefore having a narrow orbit it finishes its course more quickly. For it traverses in thirty days the journey the sun accomplishes in three hundred and sixty-five. Whence the ancients made the months depend on the moon, the years on the course of the sun.
Chapter 58. On the eclipse of the sun.
1. There is an eclipse of the sun as often as the thirtieth moon reaches the same line where the sun is passing, and, interposing itself, darkens the sun. For we see that the sun is eclipsed when the moon’s orb comes opposite to it.
Chapter 59. On the eclipse of the moon.
1. There is an eclipse of the moon as often as the moon runs into the shadow of the earth. For it is thought to have no light of its own but to be illumined by the sun, whence it suffers eclipse if the shadow of the earth comes between it and the sun. The fifteenth moon suffers this until it passes out from the center and shadow of the interposing earth and sees the sun and is seen by the sun.
Chapter 60. On the distinction between stella, sidus, and astrum.