11. In the preceding drawing, the actual shape of the moon's orbit appears to be practically a circle. As a matter of fact, it is not exactly a circle, but the difference is so slight that it is only visible in the position of the earth, which is in one focus of the ellipse, and therefore not in the center. There actually would be a slight flattening of the circle, because we are perpendicular above the earth, and therefore not straight above the plane of the moon's orbit, which itself makes a small angle with the earth's. These factors have been taken into account in composing the curve (6), i.e., the orbit as it would really appear to us from above; but they are small even in #10 and in this drawing they are not noticeable. It shows the earth (1), the moon (5), and its orbit (4); the earth's umbra (2), and its orbit (3), which now can be seen to be very slightly curved.
1 cm. in picture = 1011 cm. = 1,000,000 km.
Scale = 1:1011