Theories of the Medicean Planets Deduced from Physical Causes

moderate. Therefore, the cycle of the Anomaly Anomaly: the variation in a planet's speed as it moves along its orbit, caused by its distance from the center of motion can be divided into four parts. From point A to B, the motion will be slow but increasing until it reaches a moderate speed near B. From B to P, the motion similarly increases from a moderate to a high speed. Conversely, from P toward D, the motion is fast but decreasing, and finally from D back to A, it is moderate and decreasing.

There is also a third cycle, the cycle of latitude, which begins at the ascending node Ascending Node: the point where the Moon crosses the Ecliptic from south to north D. As the Moon advances through A, B, and P until it returns to that same node from which it departed, we find that this motion of latitude is faster than the periodic motion relative to the Zodiac and far more rapid than the cycle of anomaly. From this, it is evident that Node D is not fixed or immobile. Instead, it moves in a retrograde course Retrograde course: motion in the opposite direction to the usual path of the planets against the order of the signs, traveling from East to West original: "ab Ortu scilicet ad Occasum". This motion is slower than the motion of the apogee, specifically moving about 3 minutes of a degree each day. This fact is clearly demonstrated because we observe the Moon at any given point in the Zodiac having a Northern latitude original: "Septentrionalem" at one time, a Southern latitude original: "Meridionalem" at another, and finally sometimes no latitude at all when it is found exactly on the Ecliptic Ecliptic: the sun's apparent path, where eclipses occur. Therefore, the cycles of latitude from Node D back to the same Node D are completed in a span of 27 days, 5 hours, 5 minutes, and 36 seconds. These are the Moon's own proper motions within its eccentric orbit.

Now it remains for us to consider the motions and appearances produced by the Sun upon the same Moon, according to where the Sun is found in different parts of the Ecliptic.

Once again, imagine the Moon at point A while the Sun is positioned at point S, with the Earth standing between the two planets. This occurs during an opposition, or a full moon original: "plenilunium". Let the Moon complete its entire period by traveling through the whole cycle A-B-D-A. During this time, the Sun does not appear stationary at the same point. Instead, the Sun is seen to have moved through almost an entire sign of the Zodiac to point L. Therefore, the Moon will not yet have reached point E, the position directly opposite the Sun. It will fall short by the entire arc A-E. For this reason, to reach the second opposition or full moon, the Moon must travel through that additional arc A-E. Consequently, the time between one full moon and the next consists of 29 days, 12 hours, 44 minutes, and 3 seconds. This is called the monthly or synodic course Synodic course: the time required for a celestial body to return to the same position relative to the Sun as seen from Earth.