Skyscript Astrology Forum

I recall reading how the zodiacal releasing periods are based on a 360 day year, with the 360 day year having some kind of special underlying philosophical logic. Well, while reading a non-astrological book (The Hand-Sculpted House, page 55) I came across an interesting passage:

Finally, not long ago, I watched a tree inch across the full Moon, counting seconds. Curious, the whole transit took almost exactly 4 minutes. Time it again, with the watch: 241 seconds. Four minutes is a fifteenth of an hour which is a twenty fourth of a day. Tossing the figures in my head, then Good Grief! 15 x 24 is 360! The face of the Moon spans exactly one angular degree. What a strange coincidence! Wait a minute . . . of course it's not a coincidence; we divide the circle into 360 because there are 360 moons around one complete rotation. I've heard other explanations, but this makes a lot of sense to me.

If this observation is true, does this have some kind of astrological significance? I have gaps in my knowledge of the philosophy underlying Hellenistic Astrology so I don't know how to contextualize this information and I was hoping that someone might understand how this information fits in the larger picture.

Hi there - this sounds like nonsense to me.

The moon actually moves approximately 13 degrees in a day. There are 24 hours in a day. This seems to suggest that the moon spans roughly half a degree surely. (13 / 24 = 0.54) Put another way: the Moon moves through one degree in approximately two hours - 1 / 2 = 0.5.

From J Mayo: The Astrologer's Astronomical Handbook, p 98.

"The Sun's semi-diameter (radius) varies (according to the Earth's distance from the Sun) between 15.8' and 16.3', while the Moon's semi-diameter varies between 14.7' and 16.8'."

If we double these values we get approximately 30' (minutes of arc) or half a degree for the full diameter of each of the Sun and the Moon when viewed from the Earth.

The approximately similar values for the diameters of the Sun and the Moon when viewed from the Earth gives rise to the phenomenon of Solar Eclipses, as the body of the Moon obscures the light of the Sun from us when it passes in front of the Sun.

https://www.timeanddate.com/astronomy/m ... -hand.html

Angular Size

Angular size or angular diameter of a celestial object is the angular separation between opposite edges of the object. The Sun and the Moon are the only objects in the sky whose angular size is visible to the naked eye.

Remember to never look at the Sun directly without any eye protection!

The angular diameter of a full Moon is about 30', while the angular diameter of the Sun is around 32'.

To return to the author's experiment referenced above - the only thing that they have proved is that the angular size of the width of the trunk, viewed at a particular distance, is about one degree. To do this experiment accurately, the observation that needed to be made was the time taken between the first contact between the edge of the full moon and the trunk of the tree, and the time when the moon disappeared behind the trunk. My guess is that this would have been approximately 120 seconds or two minutes.

https://www.wku.edu/eclipse/duration.php

Solar Eclipse Duration

How Long Does a Solar Eclipse Last?

It takes hours for the Moon to move completely between the Sun and Earth, but the time when the Sun is completely covered lasts no more than a couple of minutes for any given location.

Thank you for your detailed response astralwanderer! I admit that I lack experience actually observing astronomical phenomena like this; instead I'm more accustomed to looking at a nice and tidy 2D representation of the sky . Your response approached the OP from a different angle than I expected, however it got me thinking about the issue differently as well and I made some interesting observations of my own:

1.He mentions it took four minutes for the transit to complete. This sounds to me like he mistook the rotation of the Earth for the movement of the Moon. I think that would be an easy mistake for a layperson to make, or anyone that's not accustomed to sky watching.

2.The Moon can appear to be larger or smaller depending on its location in the sky. Even though it's actually 30' it can appear to be wider than that. In light of that, I wonder how ancient astrologers conceptualized the width of the Moon? I'm a strong proponent of considering the 'apparent reality' of astronomical phenomena as seen by the naked eye as opposed to only considering cut and dried astronomical facts. My reasoning for this is the same reasoning for only using the classical seven planets (which of course are the only planets that are visible to the naked eye). It seems like astrology as practiced by the ancients was intrinsically centered around the human perspective.

This brings to mind the Greek optical theory, which we now know is scientifically incorrect but it's still correct in this strange kind of metaphysical way, as can be evidenced through the functioning of the planetary aspects. It seems like there's this fuzzy layer of reality where abstract concepts and physical reality mesh together, or at least this is my impression of it.

I freely admit that I'm out of my element here dealing with these kinds of particular technical details. Ultimately I'm just trying to take this guy's observations at face value and see if he has a novel perspective that would otherwise slip through the cracks for anyone not there in person observing the actual event.

Hi Kubernetes - no problem. There are a complex mix of factors, especially proximity of the Moon to the Earth, which alters the angular size of the moon. This variance lies behind the interesting concept of the 'super moon'. The closer the Moon to the Earth, the larger it's angular size. When the Moon is about 10% closer to the Earth (I think that's right) than average it's counted as a super moon.

https://en.wikipedia.org/wiki/Supermoon

The astrologer that popularised this concept is Richard Nolle.

https://www.astropro.com/features/articles/supermoon/

It's an interesting point about the potential to confuse the rotation of the Earth with the motion of the Moon - I can see how that could happen. This is of course the difference between primary and secondary motion. My view is that the experiment described by the author above is principally about primary motion 'carrying' the Moon past the tree which appears as a fixed object. The unintentional error was that the trunk was two 'moon widths' wide to the observer.

According to him it took four minutes for the full moon to pass the tree, and four minutes is equal to roughly a degree of primary motion right? So logically speaking, the full moon should also be roughly a degree wide; obviously it's not, but for some reason this is what the author saw. Again, I'm out of my depth here so I'm not going to defend my point too strongly but I think this is one of those situations where I'll have to conduct the experiment myself (with my own naked eye) to see what he's talking about.

Hi Kubernetes

I've had a good night's sleep so I can see that my reply could do with a bit of clarification:

Secondary motion of the Moon - 30' of longitude per hour, or roughly 12-13 degrees per day.

This hourly rate of secondary motion is coincidentally (or not from a symbolical point of view) the same as the Moon's apparent angular size when viewed from Earth.

The author's experiment uses the tree in an attempt to measure the angular size of the Moon when viewed from Earth. The experiment uses the primary motion of the Earth's rotation to carry the Moon passed a fixed object. The rate of primary motion is, as you point out, one degree of longitude over the meridian every four minutes.

The methodology was half right - noting the time of the beginning of the disappearance of the Moon behind the tree - but the clock needed to stop when the Moon completely disappeared behind the same edge of the tree, not when it reappeared the other side.

For accuracy, it would probably be helpful to use an object more or less aligned with the observer's meridian.

If the author had used this approach, I'm fairly sure the elapsed time would have been around 120 seconds, give or take a few depending on the proximity of the Moon to the Earth. I'm fairly sure this would give an angular size for the Moon of 30' or half a degree, based on the rate of primary motion of one degree of longitude over the meridian every four minutes (240 seconds).

If we were to do the same experiment with the Sun, and I can't recommend this at all without specialist protection for the eyes, my guess is that it would take around the same time to disappear behind the edge of the tree, establishing that both Sun and Moon measure the same angular size in the sky when viewed from Earth.

I'm still thinking about the eclipse example. I'm not sure how relevant it is in this context.

It is all very complex, but broadly speaking I think the above is correct. Apologies for any confusion in the original post.

Thanks! I understand what's happening a lot better now. Thinking over it, I can see why he believed the Moon was one angular degree in width, it's even easier for this misunderstanding to compound when reading about it instead of seeing it in person.

While taking into account the facts you brought up something occurred to me. The guy (mistakenly) talks about how there would be 360 full moons equal to one degree around one complete rotation of the Earth, however with some tinkering his observation might be viable.

Assume it's around the equinox and imagine having 360 30' Sun segments during the daytime and 360 30' full Moon segments during the nighttime which when added up (by combining appropriate segments as oppositions) would equal a full regular 360 degrees. It seems like the positions of the luminaries (and their unique angular size of 30') while in opposition can be used to infer a giant circle composed of 360 unique oppositional segments, which is where I assume we get the logic for a 360 degree circle from. Using this concept, we have an elegant, plausible explanation of the 360 number that relies on a beautiful symmetry of solar and lunar symbolism.