Talk:Moon

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The structure among the sections is chaotic and illogical.

1. I don't think that the untitled first section of "Physical characteristics" serves the proper role of introducing the rest of the section; rather it seems like it was thrown there bcz the contributor didn't think thru what to relate it to, or thot their own contrib should be placed as prominently as plausible. Instead, it seems to me to belong as part of the "Orbit and relationship to Earth" sub-secn.
2. The section "Orbit and relationship to Earth" perhaps should be retitled "Relationship to Earth", and ...
3. ... it would have its current lead subsection as a titled subsection "Orbit".
4. The section "Appearance from Earth" should be demoted to be another subsection subordinated to "Relationship to Earth".

So far, i don't see much reason to be concerned to change the order of sections, or of subsctions w/in their secns, tho that might emerge as something that could be done better.
--Jerzy•t 12:28, 17 August 2010 (UTC)[reply]

   In doing the edit that requires, i also am moving out of the caption on the diagram of the earth-moon system all of the prose:

The axial arrows give the direction of axial rotation. Note that the axial tilt of the Moon is shown in the same direction as that of the Earth (it appears reduced only due to the similar magnitude of its orbital inclination).

It was a poster-child for the desirability of noun phrases rather than sentences in captions, bcz the format would become awkward with the amount of info needed to communicate those ideas well, and the diagram is primarily useful re orbital motion, with rotation previously being un-discussed in the section with the diagram and most relevant to the Earth-relationship-irrelevant "Seasons" section (which -- see #Seasons below -- i'm moving to "Physical characteristics", and where i'll eventually, if others don't, put some new rotational-axis prose).
--Jerzy•t 09:57, 24 August 2010 (UTC)[reply]

I think it's important to mention that 'the Moon is the largest moon in the Solar System' a little earlier in the article, because that ties into why it is differentiated, why it can have a 2000+ km sized crater without having fractured like Miranda, etc. I will work on a paragraph that can go at the top of Physical characteristics that makes this clear, incorporates the material in Relative size, and provides some introduction. The planet-satellite bit can go as a footnote. The other article rearrangements are good. Iridia (talk) 01:12, 25 August 2010 (UTC)[reply]

The fact that "the Earth's day lengthens by about 15 microseconds every year" is not the reason for "the occasional addition of a leap second to the calendar." Positive leap seconds are needed now because, in recent times, the second was redefined to be slightly shorter than 1/86400 of an average solar day. The lengthening of the day due to the Moon will--very slowly--increase the rate of leap seconds, which is now about 1 every 1 1/2 years. But, if the tidal effect of the Moon on the Earth were to cease right now, leap seconds would continue to occur. —Preceding unsigned comment added by 208.53.195.38 (talk) 20:42, 18 August 2010 (UTC)[reply]

I've changed it to hopefully make more sense. That clause seems a bit long now but I could not immediately think of a more concise way to express it.--JohnBlackburne^words_deeds 21:07, 18 August 2010 (UTC)[reply]

It looks great to me, John. —Preceding unsigned comment added by 75.54.81.31 (talk) 01:21, 19 August 2010 (UTC)[reply]

The problem is that leap seconds have nothing to do with the calendar. The mean year length in the Gregorian calendar, for example, is exactly 365.2425 days, whether or not there is a leap second. A single year has 365 or 366 days, the elemental unit of a calendar. Leap seconds affect the clock, not the calendar. I changed this, but the change was reverted. Is there an explanation for this? Victor Engel (talk) 21:08, 23 August 2010 (UTC)[reply]

You're right - although it only happens annually the leap seconds are added to the length day, to make that day one second longer. This needs to be done less than once a year so is done for convenience (I guess) on Dec 31 when needed, but again to the clock. The name "leap seconds" also suggests the calendar, just to be helpful. I've changed it based on the wording at leap second with another link as it's perhaps clearer than just 'clock' or 'calendar'.--JohnBlackburne^words_deeds 21:26, 23 August 2010 (UTC)[reply]

I think that's a good solution. Thanks for the change. Victor Engel (talk) 21:30, 23 August 2010 (UTC)[reply]

? —Preceding unsigned comment added by 156.34.186.192 (talk) 05:06, 21 August 2010 (UTC)[reply]

In a word, no. The Earth does have a slight gravitational wobble due to the Moon's orbit, just like anything else that is orbited by anything, but it doesn't orbit the Moon. You could make a case for the Moon orbiting the Sun, though. Serendi^podous 06:38, 21 August 2010 (UTC)[reply]

They both orbit their common centre of gravity. But as the Earth is much more massive than the Moon this centre of gravity is inside the Earth, resulting in a a wobble around this point for the Earth and the Moon orbiting the Earth at a much greater distance.--JohnBlackburne^words_deeds 10:08, 21 August 2010 (UTC)[reply]

Lack to mention the observations of Keppler and Hevelius - and other old astronomers- about the phenomenon of " disappearance of the Moon" in the firmament, in completely cleared days, that to say without clouds. These astronomers already knew the moon phases and everything the knowledge about the orbit. Therefore these astronomers attributing the " disappearance of the Moon" to an "atmosphere in moon" that hid the Moon to the telescopes. I think is very interesting reviewing the previous thing, for the dedicated ones to this subject: the Moon. —Preceding unsigned comment added by 163.247.80.9 (talk) 14:23, August 23, 2010

   Kepler, OK; Johannes Hevelius was apparently famous in astronomy primarily for his lunar work. But the above is so awfully vague as to be of use to no one but specialists. Give us a hint so research can be considered: what did they already know about the phases? Is the "disappearance" we are talking about the new moon, the eclipsed moon, or the invisibility of the moon during most of daylight (which is due to the light scattered by the earth's atmosphere creating a blue sky brighter than the moon)? What works mention this, and what exact words do K & H each use to describe the phenomenon?
--Jerzy•t 05:37, 24 August 2010 (UTC)[reply]

Well. I am not astronomer, but the mentioned possibilities for those who were responsible to the note, already I thought it, but I misestimated it because a thing is that the astronomers are old, but other is lack to perspicacity in these astronomers. I do not believe in that last possibility.

I can add, for further possible investigation, that there are one more astronomer that mentioned the phenomenon in question: Ricciotti (Rudy?). Unfortunately I have not the exact source of their claims. If I had, I would have dared to write directly a part of the article. As to whether this topic is too specialized, it must be evaluate it by the authors of the article. But my view is that an encyclopedia like Wikipedia is slowly changing the model of encyclopedia in general. Many articles of Wikipedia are written more extensive than before in any encyclopedia than ever before were written. This is fine. Thus, not only the uneducated but the specialist in any field of philosophy or science, or art, (or also the finder of finer or specific data) can enter a particular item and find interesting facts. Searching is necessary in this specific topic. —Preceding unsigned comment added by 163.247.80.9 (talk) 13:34, 26 August 2010 (UTC)[reply]

   I found

Although the Moon's minute axial tilt (1.54 degrees) means that seasonal variation is minimal, it is just enough to create a 3-degree variation in the Sun's elevation at the poles, resulting in a very slight "summer" and "winter".

but the cited ref at 'Coldest place' found on the Moon doesn't support "just enough" (except combining the imprecise sense of "just" with the trivial fact that 2×1.54≈3).
   Discussion of this requires dealing with distinction between its tilt relative to its orbit around the earth (6.68 degrees) and its tilt relative to the earth/moon system's orbit around the sun; i am not yet confident that subtracting the 5.14 degree tilt between the two orbits (to get 1.54) is valid, even in light of the tidal lock, rather than one of the numbers being some WP editor's defective original research, so i'm deferring writing all that is probably called for about angles. I think whoever wrote the caption blew it, and the 3-degree variation applies at lunar noon at all latitudes. In any case, the real story is not seasons but the near immunity of some near-polar points to summer increases.
--Jerzy•t 09:57, 24 August 2010 (UTC)[reply]

"The Moon's axial tilt of 1.54 degrees produces much less seasonal variation of illumination than the Earth's 23.44 degree tilt" How much lunar seasonal variation does Earth's 23.44 degree tilt cause? Seems to me it's essentially zero. If that's not what was meant by that statement, I suggest the statement needs to be clarified. Victor Engel (talk) 20:15, 24 August 2010 (UTC)[reply]

It seems clear to me. The Moon's axial tilt affects the Moon, the Earth's axial tilt affects the Earth, and that's what it's comparing: the lunar seasonal variation, if any, with that of the Earth which is significant (at least here in England). I don't see any problems with the angle. Orbit of the moon goes into more detail on the reasons why it has that value and gives a more precise value of 1.543° and a ref. I'm sure this will be covered in a more accessible form, such as a good general reference on the solar system or Moon. here's another source that mentions it for example. Looking at it as a whole I can't see major problems with that section.--JohnBlackburne^words_deeds 21:45, 24 August 2010 (UTC)[reply]

Thanks. I modified the sentence so that it's clear the Earth's tilt refers to Earth's seasons, not Moon's seasons as was implied by the previous wording. It's a bit clumsy as is. If someone think of a way to say the same thing less clumsily, please do. Victor Engel (talk) 21:55, 24 August 2010 (UTC)[reply]

   Thank you, Victor, for fixing that ambiguity, which escaped my notice. (But I urge you against the slangy misuse, on WP, of imply where there is merely insinuation or (as here) wording that creates the occasion for someone to invalidly infer something.)
--Jerzy•t 09:18, 25 August 2010 (UTC)[reply]

The word "imply" is not slang. It was a word carefully chosen to describe the essence of the problem with the sentence. That word is both accurate and efficient. Besides, this is a talk page. Victor Engel (talk) 14:01, 29 August 2010 (UTC)[reply]

   I removed:

There are several known near-Earth asteroids that have unusual Earth-associated horseshoe orbits: 3753 Cruithne, 54509 YORP, (85770) 1998 UP1 and 2002 AA29.^[1] They are co-orbital with the Earth, so that their orbits bring them close to Earth for periods of time but then alter in the long term, and they are not natural satellites of Earth.<ref>Connors, Martin (September 2002). "Earth coorbital asteroid 2002 AA29". Retrieved 16 April 2010. {{cite web}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)</ref>

This is relevant to Other moons of Earth, and presumably covered there. It is a non-sequitur where i found it (Moon#Orbit and relationship to Earth, which i moved to Moon#Orbit, and does not deserve more than footnote mention (which already occurs at "nb4", a footnote to the lead sent).
--Jerzy•t 10:11, 24 August 2010 (UTC)[reply]

I have rescued the deleted ref to a peer-reviewed article and added it to the lead footnote. That text was in the article before the lead footnote was added. Iridia (talk) 02:10, 25 August 2010 (UTC)[reply]

I modified the description of the image on the moon page. It's not, in fact, a full moon image as was previously indicated. You can tell by looking that it's not a full moon. Additionally, the date/time of the image is the evening following the date of actual full moon that month. I suggest another full moon image be used if one is available. If not, I may contact some photographer friends to possibly upload another one. Victor Engel (talk) 15:53, 26 August 2010 (UTC)[reply]

There are a few on commons like File:FullMoon.jpg, File:Full moon.png, all from the category commons:Category:Full moon. But I don't have a problem with the current image: it's not so far off a full moon that anything is obscured, and the slight angle between the sun and the viewer adds shadows to the right side which usefully highlights craters. There is also an article full moon for those readers more interested in that particular phase of the moon.--JohnBlackburne^words_deeds 16:15, 26 August 2010 (UTC)[reply]

Thanks. I agree, the image is fine for the article, as long as it's not identified as a full moon. Just noticed the same image is used in the full moon article you cited, so I removed it from that article. Victor Engel (talk) 16:59, 26 August 2010 (UTC)[reply]

Both sides of the moon get exactly the same amount of sunlight? Can someone please either explain how that is possible, or find a reference that is accurate? As far as I knew, though the amount of sunlight is similar, it isn't exactly the same (or even nearly exactly the same). Something to do with the Earth being in the way when the near side of the moon is on the night side of the Earth, reducing the amount of light hitting it (what we know as phases).

Meanwhile, when the far side of the moon, when it is turning towards the sun, is not being blocked by the Earth (to nearly as large of an extent).

Perhaps I am misremembering my astronomy class. Hence my two part question above.

Thanks, RobertMfromLI | User Talk 03:38, 29 August 2010 (UTC)[reply]

Yes, "exactly" is too strong. The near side is sometimes shaded by the Earth (during a lunar eclipse), but the far side never is. The near side does benefit from sunlight reflected from the Earth, if you count that, while the far side does not. And the division into "far side" and "near side" is not a true dichotomy, due to libration, which makes the situation even more complex. Still, the purpose of the sentence you've queried is to debunk the idea that there is a "dark side of the moon", and with that in mind, I think "exactly" is a reasonable simplification. (Perhaps "essentially" would be better.) We should at least add a caveat in a footnote, though. --Avenue (talk) 09:11, 29 August 2010 (UTC)[reply]

   That response helps a great deal

Hello. The lunar phase during the last quarter of the synodical cycle is called "waning crescent" in this article, and in some other pages, too. I didn't like this phrase so I have looked it up in my dictionary, and I found "decrescent" there. The "waning" and the "crescent" (increasing, greatening, waxing) are definitely contradictive words, the opposite direction of a "crescent" motion is "decrescent". So, I made a new (and proper) illustration about the phases, and I really would like to use the most and only correct phrases on that. I ask the native English speakers this question: which version is the correct, the official, the commonly used? Or if "decrescent" is as good as "waning crescent", am I allowed to change that in the text? - Orion 8 (talk) 21:12, 29 August 2010 (UTC)[reply]

In my opinion, waning crescent is better than decrescent. My firefox dictionary doesn't even recognize decrescent as a word. It's counterpart should be increscent, not crescent. Etymologically, increase and decrease both have the same root as crescent does, so I really don't see the problem with the word. First crescent is extremely important in certain cultures because it determines the calendar. So the first crescent is more significant than the last crescent (last crescent is the last visible sliver before new moon, not the phase just before first quarter or even just before full, which would be the alternatives if they must be increasing). Victor Engel (talk) 02:01, 30 August 2010 (UTC)[reply]

P.S. Increscent and decrescent are adjectives. Crescent is a noun. This is going to sound really redundant, but the first crescent is an increscent crescent. The last crescent is a decrescent crescent. Victor Engel (talk) 02:06, 30 August 2010 (UTC)[reply]

I'm a native (British) English speaker, and 'waxing crescent' (or 'crescent waxing') and 'waning crescent' sound natural to me. I'd never heard of the word 'decrescent', though on looking it up in the OED I find that it's the antonym of increscent. The OED also gives two separate meanings for 'crescent' - one specific to the waxing moon, and one for either waxing or waning. My experience is that the latter is the more commonly used, so 'waning crescent' is no contradiction.

Also, crescent is both a noun and an adjective (as in 'crescent moon'); the OED states that the same is true of 'increscent' and 'decrescent'. Olaf Davis (talk) 11:34, 31 August 2010 (UTC)[reply]

The following contrib has had its formatting corrected (indenting it below the deepest-indented contrib that it responds to), lest it appear that the first contributor to a discussion possesses the prerogative of responding at the left margin to close it.

Thank you for your answers. All right, I receive the judgement. Although I found 'decrescent' more consequent and rational, the evolution of a language is not rational, and I will follow the language. The modified image, with 'waxing crescent' and 'waning crescent', will be uploaded soon. Üdv! - Orion 8 (talk) 00:29, 3 September 2010 (UTC)[reply]

   A spell-checker rejection is a ridiculously bad criterion for foregoing a word: i've seen the Firefox one reject a word bcz (IRCC, but if i'm mistaken it was an analogous situation) bcz (presumably) someone decided there was no need to ever use its plural form, as i chose to.
   And checking the OED is a nuclear fly-swatter -- my 1st try, the 8th Collegiate, sufficed.
   But both adjectives are preciously obscure, in contrast to the very ordinary noun "crescent" (and its equally ordinary attributive use in "crescent moon"): the adjectives have been overtaken and largely displaced by the noun derived from one of their common root (Latin crescere, to grow), and are effectively archaic terms; they are in dictionaries not to encourage their use but mainly to permit those who would not use them to understand archaic works -- and modern ones by those who imitate archaic ones.
--Jerzy•t 20:25, 5 September 2010 (UTC)[reply]

Is there an article with all the artifacts on the moon surface ? Even the smallest objects like the golf balls (?), the NASA pin and the family photo in the zip bag, it would be interesting to have one. --79.168.10.241 (talk) 07:03, 17 September 2010 (UTC)[reply]

There's List of man-made objects on the Moon, but it doesn't list the smaller objects. Still pretty interesting, in case you haven't already seen it. --Bongwarrior (talk) 07:12, 17 September 2010 (UTC)[reply]

Thanks. --79.168.10.241 (talk) 17:46, 19 September 2010 (UTC)[reply]