July 5, 2019

# #2172: Lunar Cycles

Understanding lunar cycles

Nodal precession

[A diagram showing a broad cosine-like wave with wavelength labelled as 18.6 years. To the right are two diagrams showing an orbital cycle moving in and out of plane.]

Apsidal precession

[A diagram similar to the one above but with a slightly shorter wavelength, labelled as 8.9 years. To the right are two diagrams showing an elliptical orbit around a planet and the same orbit rotated.]

Phase

[A diagram similar to those above with a shorter wavelength, labelled as 29.5 days. To the right is a diagram showing four phases of the moon: New, Waxing crescent, Waxinf gibbos, Full.]

Distance

[A diagram similar to those above with a shorter wavelength, labelled as 27.5 days. To the right is a diagram showing the distance of the moon from the Earth over time, with distances marked by arrows.]

Earth-Moon relative size

[A wave with long wavelength with an arrow pointing to the minimum labelled ‘Earth bigger’ and an arrow pointing to the maximum labelled ‘Moon bigger’. To the right are two diagrams of the moon and Earth, one showing the Earth bigger than the Moon and the other showing the Moon bigger than the Earth.]

Lunar shape

[A wave with long wavelength with an arrow pointing to the minimum labelled ‘Circle’ and an arrow pointing to the maximum labelled ‘Square’. To the right is a diagram showing a circle, a circle transforming into a square with outward arrows at each corner and a square transforming into a circle with inward arrows.]

Lunar mood

[A wave with long wavelength with an arrow pointing to the minimum labelled ‘Bad’ and an arrow pointing to the maximum labelled ‘Good’. To the right are four emojis: :), :|, :(, :|]

[A superimposed graph of all the above waves. Different points on the graph are labelled: Harvest moon, Supermoon, Blue moon, Skinny Jeans popular, Super blood moon, Golden age of TV, Dire moon, Pork moon, Two week window in which astrology works, Total eclipse of the sea.]