Ethymological and technical question about lunar phases and phases in general

[Jean]

The real reason I'm creating this topic, is because I have a lot of enjoyment making theories about fromsoftware games, and sharing them and reading other people theory. I think this pleasure is made rare today because how easy it is to know everything about most mundane topics.
I recently realised that if tree can probably feel moonphases, it is because they are a bunch of capilary pipe, so they can probably feel the gravitational influence of the moon, and they can also probably feel how much light they are getting. Those two thing have a cycle of similar time, but not exactly, so where those two cycles are relative to each other are what we call moonphases.
In common language, a phase is something that is temporary, (like saying someone is having a Goth phase), but not necessarily cyclical.
When we talk about phase in a technical setting, in means how two cyclical things of similar period are in there resepective cycle relative to each other.
What i wonder, is if phase had originaly the "comon" meaning, and it got the technical meaning when we realised that two wave that don't exactly have the same period was something similar to moon phases, so we used the word phase for that. Or if phase always implied two cylcling drifting away and back together.
Also Is "second order phase" the correct way to describe when a phasic cycle is having his own phase with an other cycle (like how a lunar cycle an menstrual cycle are slowly drifting, when a woman is menstruating during full moon, next cycle one day after, and so on)?

[jacob]

I'm not entirely sure where you're going with this, but I'll give you something to work with.

In SI-units,
G = 6.67e-11
Mearth = 5.97e24
Msun = 1.989e30
Mmoon = 7.35e22
Rsun = 152e9
Rmoon = 384e6

The gravitational force (acceleration) from the different objects is giving by g=GM/R^2. However, the tidal pull is the difference between the force at the top end and the bottom end. So for a 10m tall tree, it would be delta g = GM(1/R^2-1/(R+10)^2). If you do the calculation, you'll find that this is a tiny insignificant number. Also note that the tidal force increases with distance. That's how the tidal force affects oceans (on opposite sides of the earth) but not trees.

Fun stuff: Do the same for the sun. Note that the tidal pull from the sun is smaller than from the moon but not that much smaller. Thus the moon drives the tides, but the position of the sun (in the sky) also matters.

More fun stuff: Compare to the total gravitational force (different than tidal force) from the three objects.

Phase is used in two different ways, space and time.

1) Matter is in the same phase if thee physical properties across a region of space is uniform. Like an ice cube in a glass of water. The ice is in one phase of matter and the water is in another phase. As the ice melts, it undergoes a phase change.

2) Phase is also used if something is periodic in time, that is, f(t)=f(t+T), where T is the period, t is time, and f is whatever function but usually described as an angle.

It's also possible to add two periodic functions with the same period to get one function with the same period (and a phase shift). Once you start adding functions with different periods, you get resonances and interference.

Note that the tidal phase from the moon and the sun depends on the earth's rotation(*), so roughly 24 hours. The lunar phase (space sense: how much is lit up and how much is shadowed) depends on the position of the moon relative to the earth and sun and goes with the moon's orbital period, so roughly 29 days. Also, the light that a tree would see from the sun and the moon has the same spectrum because moonlight is reflected sunlight.

(*) More precisely the earth's rotation plus the lunar orbit. They rotate the same way, so it's closer to 24hr+24hrs/29 ~ 24.8 hours.

[Jean]

I have an other question about the moon. But my google-fu doesn't work.
When the moon isn't full, the part of the moon beyond the terminator is still visible, slighltly different color than the sky around it.
Is it because of the thin atmosphere of the moon (about 10^15 thiner than on earth)? Or is there an other phenomenon I'm not aware of?
Or is is just an optical illusion were my brain wants to complete the circle?
I don't have a good camera to test the illusion hypothesis.

[jacob]

It's lit up by "earthshine" (indirect sunlight reflected off of the earth). It is fairly easily visible in a small telescope (60mm) insofar you can blank out the much brighter part of the moon that is lit up by direct sunshine.

Add: https://en.wikipedia.org/wiki/Earthlight_(astronomy)

[chenda]

Moon and menstrual are indeed etymologically linked, as the lunar cycle almost perfectly aligns with the average menstrual cycle of 29.3 days. So historically watching the lunar cycle would be useful to women. It would also be how high tides and low tides were predicted during full and new moons, hence more food stuffs would be washed ashore from the sea and provided humans with an abundant food supply for no work at all. And the moon gave light at night before electric lights, another bonus. I also knew an Italian who insisted bottling wine around the time of a full (?) moon would cause it to fizz and burst out of the bottle.

This concludes my luna knowledge.

[Jean]

@jacob
It's apparently also visible with the declining naked sight of a middle aged man, since I was asking what it was
Thank you for the answer, when googling it, I was drowned under results about the hidden side of the moon (which we call dark in english for some reason). I should have thougth about it.
@chenda
I'm not sure that the average menstrual cycle is 29.3.
what I'm surprised, is since it is very often not 29.3, but still quite regular, the phase beetween one woman cycle and one moon cycle has no name. Like let's say you are ovulating at full moon, if you have a 28 day cycle, about 11 cycle later, you'll be ovulating at new moon.
That's how i do, millions of people probably already did something similar, yet there is no common name for it.

I started this topic, because a former colleague wrote a paper about felling date of wood regarding moon phase, and wood qualities, and someone insisted it was fraud because there was no way trees could feel moon phase.

[7Wannabe5]

the phase beetween one woman cycle and one moon cycle has no name

Well, women used to marry quite young, so the regularity of the cycle would be less remarkable when often interrupted by pregnancies, breast-feeding*, and miscarriages, until you finally lapsed into the irregularities associated with peri-menopause. Also, since humans are fairly unique in constantly being fertile; other primates go into heat, it's difficult to attach the similarity to moon cycle with an evolutionary mechanism. Although it is also the case that a full-term human pregnancy is 10 menstrual or moon cycles.

*Which tends to suppress fertility and menstruation, but not completely. One of the mechanisms behind the mid-20th century Baby Boom was that infant formula had been perfected and was quite popularly used in the U.S., but birth control was less perfected and less frequently used by those who were married. So, due to the Catholic prohibition of birth control, it was not infrequent for a young married woman who formula-fed her infants to find herself almost immediately pregnant again with "Irish Twins"; infants born less than a year apart. Many of the classic housewife having a complete nervous breakdown Second Wave feminism novels involved a protagonist or secondary character who simply collapsed after having too many babies too fast.

[jacob]

I started this topic, because a former colleague wrote a paper about felling date of wood regarding moon phase, and wood qualities, and someone insisted it was fraud because there was no way trees could feel moon phase.

In my first reply I keyed off on the gravitational impact of which there is almost certainly none. However, the difference in moonlight over the different phases may have an impact.

When I looked up the data for apparent magnitudes, it turned out that wiki already has an explanation
https://en.wikipedia.org/wiki/Apparent_ ... n_and_Moon

Also of (perhaps more) relevance is the difference between full moon (-12.6) and new moon (-3.69), especially compared to Venus-shine (-4.14). The full moon is bright enough to cast shadows at night. I read some old bucket list where someone talked about seeing his Venus shadow. I don't know if that's actually possible.

What's really important here is whether the luminosity (400,000 less than daylight during full moon vs ~0 during new moon) during night time is enough to change the chemistry of the tree. The reflected moonlight spectrum is practically the same as the sun, so the tree's chemistry would see it. The question, which I don't know the answer to, is whether there's a difference from a factor 400,000 reduction from daylight and effectively no light or more correctly star/Venus light. (Note that Venus light only happens during either dusk or dawn... never through the whole night.)

[chenda]

@Jean - This is the source of the 29.3 length: https://www.nature.com/articles/s41746-019-0152-7

Dendrochronology can establish in what year and season timber was felled, such as timbers in an old building.

[chenda]

@Jean - This is the source of the 29.3 length: https://www.nature.com/articles/s41746-019-0152-7

Dendrochronology can establish in what year and season timber was felled, such as timbers in an old building.