Talk:Moon

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See also

There is no See also section in this article, which is an important feature of WP, aiding in its main use, namely, to broaden the scope of a reader's inquiry. Brews ohare (talk) 13:21, 5 May 2010 (UTC)

   Well, Wikipedia:Manual of Style (layout)#See_also_section radically disagrees with your premise that a "See also section ... is an important feature of WP."
--Jerzy•t 06:00, 17 August 2010 (UTC)

Possible error

I think there is a mistake in the diagram that shows the Earth-Moon system. It indicates the distance between the two is 1738km, in fact it is over 384,000km exterminator (talk) 03:43, 5 June 2010 (UTC)

It seems to show the radius of the moon as 1738km and the distance as 384000km. -- Kheider (talk) 03:50, 5 June 2010 (UTC)

   Indeed it does, but the overcrowded diagram is an impediment to quick understanding, and an invitation to misunderstanding.
   It should be replaced with a better executed version.
--Jerzy•t 06:14, 24 August 2010 (UTC)

oblate or scalene?

Wouldn't the fact that the moon is tidally locked mean that it is a scalene ellipsoid rather than an oblate spheroid? — kwami (talk) 23:44, 9 June 2010 (UTC)

   If what you're proposing is to replace one term with the other (or retarget the data-box's ref to Flattening -- that article implies (approximation by) an oblate spheroid), don't be silly: unless you are going to talk about its degree of deviation from being spherical or whatever, these labels have been pointless since the variable shadows of surface features were identified by an astronomer (was it Galileo?) who decided the details were not worth pursuing, since even the Jesuits had given up claiming sphericality (or is it sphericity?).
--Jerzy•t 05:59, 24 August 2010 (UTC)

"Name and etymology" secn

    Some lexicography is justified, but stick to the Moon, not the other uses of "moon". The former language:

In English, the word moon exclusively meant "the Moon" until 1665, when it was extended to refer to the recently discovered natural satellites of other planets.<ref name="etymonline">Harper, D. (2001). "Moon". Online Etymology Dictionary. Retrieved 29 March 2010. {{cite web}}: Unknown parameter |month= ignored (help)</ref>

is appropriate to the article Natural satellite, but not here. (BTW, the ref is unfortunately not acceptable, bcz it doesn't serve to verify: the compiler of the site is not verifiably (nor apparently) a qualified scholar of etymology, nor does he provide the scholarly apparatus necessary to verify his assertions.)
   "Moon was a Germanic word..." was misleading bcz "Moon"/"moon" did not come into English in that form, and it is only "Germanic" in the sense that probably the majority of English words are, namely being descended from different words in earlier Germanic languages.
   The phrase "proper English name" is probably a "helpful" edit from a colleague who didn't understand the difference between that and "English proper name". We report usage, not the PoV matter of its claims to propriety.
--Jerzy•t 01:21, 16 August 2010 (UTC)

Major revision

Bloodofox has just made a significant revision to the Etymology section that appears to introduce some improvements, but also to remove some material, based on reliable sources, as to the Greek origins of the word.

Old version:

The English proper name for Earth's natural satellite is "the Moon". Moon derives from Germanic languages but is more distantly related to the Latin [mensis] Error: {{Lang}}: text has italic markup (help) and Ancient Greek [μήνας] Error: {{Lang}}: text has italic markup (help) (mēnas) both meaning month, and to [Μήνη] Error: {{Lang}}: text has italic markup (help) (Mēnē), the alternate name for [σελήνη] Error: {{Lang}}: text has italic markup (help) (Selēnē), the Ancient Greek name for the Moon. It is ultimately a derivative of the Proto-Indo-European root me-, also represented in measure (time), with reminders of its importance in measuring time in words derived from it like Monday, month and menstrual.

The names [Luna] Error: {{Lang}}: text has italic markup (help) and [Selene] Error: {{Lang}}: text has italic markup (help) -- Latin and Greek respectively, for both the sky phenomenon and the respectively Roman and Greek goddesses corresponding to it -- are used in English to personify the Moon, and imaginings of future roles of the Moon in industry or travel often use "Luna" like a geographic name for it.

The principal English adjective pertaining to the Moon is "lunar"; one sense of "selenic" shares that meaning, and "seleno-" and "-selene" are combining forms.

New version:

The English proper name for Earth's natural satellite is "the Moon". The noun moon derives from derives moone (around 1380), which developed mone (1135), which derives from Old English mōna (dating from before 725), which, like all Germanic language cognates, ultimately stems from Proto-Germanic *mǣnōn. Proto-Germanic *mǣnōn derives from the Proto-Indo-European root me-, also represented in measure (time), with reminders of its importance in the lunar Germanic calendar of the Anglo-Saxons in words derived from it such as Monday ("Moon's Day"), month and, by way of Latin, menstrual. Derived from Latin, the principal English adjective pertaining to the Moon is "lunar" one sense of "selenic" shares that meaning, and "seleno-" and "-selene" are combining forms.

I would have thought it might be best to include all info, not substitute one for the other, unless there is substantiated evidence that the sources used for the old version are incorrect. Other views? hamiltonstone (talk) 02:27, 16 August 2010 (UTC)

The word has no "Greek origins"; the native English word moon does not derive from Greek, and therefore it is inappropriate to meander on about Greek while ignoring the etymology of moon. :bloodofox: (talk) 02:36, 16 August 2010 (UTC)

Half-agree. I don't think that the etymologies of Luna and Selene are relevant, but the cognates with menas etc are relevant to the wider understanding of the Moon's significance, not just to Germanic peoples. Serendi^podous 08:10, 16 August 2010 (UTC)

At least three-quarters agree with Bloodofox, now that i've seen three of the cited references from the old version. None of them really looked to adequately source the text that was there - the online Etymology dict looks not to be a reliable source, a second was, per Serendipodous, about Selene, not Moon; the third was in greek and latin, so I'm out :-) hamiltonstone (talk) 00:35, 17 August 2010 (UTC)

No problem, Hamilton. I'm glad to help. And I'd like to apologize if I've come off as bitey; I find that the nature of the wiki tends to lend itself to that. :) :bloodofox: (talk) 00:41, 17 August 2010 (UTC)

(undent) Thanks Bloodofox for cleaning up that section. I have moved the more extensive material on the calendar to In culture so the etymology section can stay tightly focused just on moon. It replaces the less-detailed sentence on the calendar/month that was there. Iridia (talk) 01:43, 17 August 2010 (UTC)

   I endorse Iridia's subsequent Undo, whose edit summary includes

Standalone paragraph is entirely calendar, and calendar = culture. It replaces a less detailed version of the same sentence in "In culture".

especially since the former placement of the pre-Germanic material in the first post-lead section further delayed the more necessary sections, and distractingly put the calendrical material (which many will find esoteric) before the clearly "Name and etymology" material that the section is named for.
    I would actually like to see consideration of moving the "Name and etymology" section (demoted to a subsection) into "In culture": nomenclature, etymology, and indeed language as a whole are aspects of culture, in contrast to the predominant physical-science sections of the accompanying article.
--Jerzy•t 12:28, 17 August 2010 (UTC)

Okay, although I'd prefer keeping it all together, I'm fine enough with moving the material not handling the direct etymology of moon into the culture section. I've moved similar information from the 'etymology' section into the 'culture' section.

That said, I strongly disagree with merging the 'etymology' section into the 'culture' section. Terminology is crucial, and for this reason we nearly always keep the etymology sections front and center. :bloodofox: (talk) 00:14, 18 August 2010 (UTC)

Yes, it's vital to have the nomenclature & etymology up front: one of the most frequent "helpful" additions to this article involve misconceptions about it (eg. that the alternative English name is Luna). Is that sentence starting "The noun moon" now adequately cited (as the citation is midway through)? Iridia (talk) 02:11, 18 August 2010 (UTC)

Agreed, I remember responding to this Luna business in the past. And yes, Barnhart covers back to Proto-Germanic, but, in this case, he does not go as far back as the Indo-European root. :bloodofox: (talk) 05:28, 18 August 2010 (UTC)

"Physical characteristics" section

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)

   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)

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)

Leap second

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)

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)

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

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)

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)

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

Doesn't Earth orbit the Moon?

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

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)

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)

disappearance of the Moon

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)

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.

Seasons

   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)

"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)

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)

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)

   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)

Quasi-moons

   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. 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)

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)