Did you know that there are five different rhythms of the moon? The first rhythms that come to mind are probably the waxing and waning moon and the full and new moon. However, these are more the phases of the moon. Rhythm, on the other hand, can be measured in five different categories: There is the synodic, tropical, sidereal, draconic and anomalistic moon. What these terms mean is explained below.
When someone talks about the synodic moon, they are actually talking about the lunar phases that we are all familiar with. A period in the synodic sense begins with a new moon. Then the moon increases, we come to a full moon, and then the moon decreases again until it is a new moon again. At this moment, the moon is at exactly the same angle as the sun, at least as seen from Earth. The synodic lunar rhythm averages 29 days, 12 hours, 44 minutes and 2 seconds.
Ascension and descent of the moon
The tropical lunar rhythm refers to the ascent and descent of the moon. We often confuse these terms with the waxing and waning moon. However, it is the height of the moon in the sky, i.e. the angle to the horizon. This means that the moon can, for example, be waning but rising at the same time. The visible area becomes smaller, while the apparent distance to the horizon increases.
Orbit around the Earth
A sidereal period is the time it takes the Moon to make one complete orbit around the Earth. On average, this is 27 days, 7 hours, 43 minutes and 11 seconds, or just under a month. It is not important how the moon looks to us or how high or low it is, but at which position it is in the sky. After all, the moon also travels around the earth. Its exact position is determined by the fixed stars in the sky.
Intersections with the ecliptic
The ecliptic is the assumed path of the Sun around the Earth. It is also called the zodiac and has been divided into 12 equal sections occupied by the signs of the zodiac since ancient times. The moon can also cross this ecliptic. In this case, one speaks of lunar nodes or dragon points - hence the name of the rhythm for the draconic moon. With an ascending lunar node (☊) the Moon changes from the southern to the northern side of the ecliptic, with a descending lunar node (☋) it is the other way round. The period counts from one ascending moon to the next.
Distance between the moon and the earth
The Moon's orbit is sometimes closer to the Earth and sometimes further away, so the distance between the Moon and the Earth changes daily. The point closest to the Earth is defined as perigee and the point furthest from the Earth as apogee. When observing this rhythm, one speaks of an anomalistic moon. On average, 27 days, 13 hours, 18 minutes and 33 seconds pass in this period.