This is an archive of past discussions about Moon. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page.
I've noticed in the article on Mars that Mars enthusiasts have actually designed a flag for Mars, which is intriguing. Why then does the moon apparently have no flag? I propose a simple flag, simply a field of grey. It represents both the actual colour of the moon as well as its sterility. Plus, come to thing of it, I think grey is pretty much the only colour (fine, it's not technically a colour) that isn't represented on any terrestrial flag that I'm aware of. Loomis5104:57, 24 March 2006 (UTC)
Polar star trivia question.
Here's a trivia question for you, and one to which I don't know the answer. Does the Moon have a polar star, whether at the north or south pole, similar to Polaris for the Earth? If there is an answer, it might make an interesting anecdote on this page. Thanks. — RJH 22:28, 15 Apr 2005 (UTC)
It seems pretty obviously trivial (the way that term is used in mathematics jargon) to me. In other words, nothing interesting worth mentioning. Gene Nygaard 22:36, 15 Apr 2005 (UTC)
Nygaard, that's just plain mean. RJ asked a legitimate question and deserves a legitimate response. If you dissaprove of the question, please keep it to yourself. Your insulting remarks are not welcome here.Loomis5103:32, 25 March 2006 (UTC)
Using MegaStar, one finds the lunar north pole lies in a void part of Draco. The nearest object (about two degrees off) is the planetary nebulaNGC 6543. The south pole is in Dorado, very close (about 18 minutes of arc off-axis) to δ Doradus, a magnitude 4.34 star. By comparison, Polaris (α Ursae Minoris) is magnitude 1.97 and 45 minutes of arc off-axis.
Is the Sun or the Earth's equatorial bulge mainly responsible? This source states the Sun dominates, but the article is about the precession of the perigee, not the precession of the nodes. This later page states it unequivocally. In terms of perturbations, it makes sense that the Sun would dominate. Its gravity is about 5.9 mm/s² whereas the Earth's equatorial bulge tugs at it with a gravity less than 0.018 mm/s² (this latter figure is obtained using the Earth's elliptical volume minus the polar-diametre sphere, times the average density --which obviously overestimates the bulge's mass). If the Earth-induced precession term dominated, the precession rate would be far from uniform, because the tilt between the Earth's equatorial bulge and the lunar orbit varies considerably.
The change in the introduction should be improved. Although there is an asteroid "in orbit" [1], that orbit is temporary. This is one of the reasons it is still under discussion, whether that asteroid should be called a "moon" or not. We should tone down that sentence and mention that (and possible other not yet discovered objects) later in that intro. Awolf00217:20, 30 May 2005 (UTC)
According to the article from space.com, it isn't even a moon of Earth at all. Perhaps it should be mentioned later on in the article, but certinaly not in the first sentence. And if it is going to be mentioned, there should at least be a link to 3753 Cruithne in the article. Columbia 06:48, May 31, 2005 (UTC)
Personally, I think Cruithne and the like don't merit any mention anywhere near the first paragraph of the Moon's page. And it definitely shouldn't say Earth has multiple moons. At best, they're quasi-satellites. Perhaps mention them near the bottom, with articles linked to accordingly. --Patteroast07:30, 31 May 2005 (UTC)
I've moved it right down to the bottom of the page. I also added that astronomers don't consider it a moon, but I haven't surveyed them all so if anyone knows of exceptions we can change it to "most astronomers". Bryan 08:35, 1 Jun 2005 (UTC)
The title image
While it is a "featured picture", the main image does appear a bit soft to my eyes. I have uploaded a potential replacement and stuck it beside orbital elements table. mdf22:45, 14 July 2005 (UTC)
Moon was created discussion
Guys, what are you doing in Origin and History?? Just because someone believes that the Moon was "created," it does not follow that this explains how!! I understood this section as a "how" discussion, which is a scientific question! Please, take your Creationism discussion to those pages and do not muddy the waters, here. Awolf00215:22, 2 August 2005 (UTC)
Alternately, we could add a creationism blurb to every noun in Wikipedia... I thought the "magnetic tides" part was rather neat though. But wouldn't it have been easier to just create the tides themselves and do away with the "middle moon," so to speak? :o) Chris15:47, 2 August 2005 (UTC)
I see no reason whatsoever for this to be omitted. Some say it's an "incredible coincidence" that the Moon is 400 times smaller than the Sun and 400 times closer; some say it's due to a divine architect. What's wrong with including a mention of creationism here, Awolf? --Golbez 21:18, August 2, 2005 (UTC)
This discussion is not about "supressing a view," but to find its correct place at WP. Since I still think the section in question is about scientific theories, this text does not belong there. Science looks for "natural explanations" by definition. Find a better place, please! Awolf00221:22, 2 August 2005 (UTC)
By better place, do you mean a better place in the article, or another article? --Golbez 21:28, August 2, 2005 (UTC)
Well, good question! Maybe we should explicitly split this into two sections! The "scientific" one, as it is now, and the "alternative" one. The wording/title can be discussed. I just don't see the point in mixing these. Awolf00221:33, 2 August 2005 (UTC)
Considering that the "alternative" one consists of one sentence, I think that's a major overreaction. --Golbez 21:48, August 2, 2005 (UTC)
Really? Whatever you do, make sure this new section is about "how," not about "why." Obviously, things can be created through natural processes and still have been made for a reason. The question about a reason for sure does not fit in this article. That's theology IMO. If all you have is this one sentence, it should go to a different article. Awolf00221:55, 2 August 2005 (UTC)
I don't understand your objection. Perhaps I don't understand the premise here; what is the complaint? That someone said that many people believe the Moon was divinely created just where it is? And is your complaint with having this sentence at all, or having it in that particular location in the article? --Golbez 22:03, August 2, 2005 (UTC)
Here is the reverted text: [The Moon's] origin is the subject of strong scientific debate. (Adherents of Creationism simply state that the Moon was created by a higher being.) Is it not obvious that this a very unhelpful (to say the least) sentence? What does it say? Creationists are not interested in the scientific debate? Or do they have a different explanation for it? How does this statement then answer the question? It just does not make sense there! Awolf00222:11, 2 August 2005 (UTC)
Golbez, what you propose now seems to try to address the angular size match of the Moon and the Sun. That does not seem to be the question of this section. In fact, currently this article does not mention the angular match as a problem. Do you plan to move this to "Eclipse"? I'm guessing what you are thinking of is something like: "Creationsts views on the properties of the Earth-Moon system." Maybe it should have its own article and a "See also" link in here? Awolf00223:34, 2 August 2005 (UTC)
You're ascribing motives that don't exist. I wanted a single line that explained that, hey, a lot of people think the moon was put there, and not formed by the admittedly wild and improbable processes that formed it. It mentions the angular match as a coincidence - it USED to say there "by coincidence or divine design". One line. All I ask. --Golbez 03:33, August 3, 2005 (UTC)
Okay, so does "put there" mean: A lot of people think the Moon materialized out of nothing in its current place and shape on accord of divine action? Is that what you want to describe? And if yes, is that "Myth" or "Science"? Awolf00214:58, 3 August 2005 (UTC)
Pretty much. Isn't that what religion is? I've turned the statement around. Move it to Human Understanding if you want. --Golbez 16:16, August 3, 2005 (UTC)
Sounds reasonable, however, all but the "Scientific understanding" section are like "See also" with basically a link to another article. Is that what you think of? Or real text? Awolf00200:50, 3 August 2005 (UTC)
I was thinking of real text, actually. On a different note, I find those current existing sections kind of... empty and messy at the same time. A nice little rewrite there would do miracle. The link to lunar astrology should be moved to the "See also" section and the mythology and muse sections could be expanded and a seperate "Creationist views" or "Modern day mythology" could be added then. I'd presume that a paragraph or two can be filled with creationist views on it and if we name it as "Modern day mythology", we can also throw in some tidbits of info about the understanding of the moon from the viewpoint of other religions. In short, what I'd like to see is a padded "Ancient mythology" section, a nice "The moon in culture" section (muse is kinda olde-english, this is clearer IMHO) and a "Modern mythology" section with creationist, Intelligent Design and other religious explanations. Opinions? :: DarkLordSeth01:29, 3 August 2005 (UTC)
Do we label all modern religious views as myth? --Golbez 16:16, August 3, 2005 (UTC)
Well, according to the dictionary definitions of mythology ("A body or collection of myths belonging to a people and addressing their origin, history, deities, ancestors, and heroes") and myth ("A traditional, typically ancient story dealing with supernatural beings, ancestors, or heroes that serves as a fundamental type in the worldview of a people, as by explaining aspects of the natural world or delineating the psychology, customs, or ideals of society"), it sure seems the correct way to refer to modern religions. :: DarkLordSeth16:56, 3 August 2005 (UTC)
Perhaps once we get enough material about the subject, but I don't think we'll be able to fill out a whole article on it's own. The creationist point of view about it is very terse to start with, ie "God did it.". However, should there eventually be enough materials about this subject, we can always move it to it's own article. :: DarkLordSeth16:56, 3 August 2005 (UTC)
The statement "In part due to its arguably unusual origin, and the coincidence in size that allows for a total solar eclipse, some people believe the Moon was created by a deity." has been removed. Here is why:
It assumes facts not in evidence - no one knows whether or not the origin of the Moon was in any way "unusual",
Even if it was "unusual", there is no reason given as to why this should, in and of itself, cause anyone to "believe the Moon was created by a deity"
Even if a deity did the deed, the statement further assumes that the acts of this deity would be "unusual" at least in this instance; where is the evidence to support this claim?
The 'coincidence in size that allows for a total solar eclipse' ignores the fact of annular eclipses, and furthermore ignores the fact that there are more annular eclipses (33%) than total eclipses (27%), and that the situation is only 'getting worse'
The unspecified reference to 'some people', and the general tone, and the aforementioned logical problems, the link to creationism, etc, all strongly suggest that this is just a heap of weasel words intended to get religious claptrap into an otherwise scientific section of the article. mdf23:39, 5 August 2005 (UTC)
Excuse me, but is it not true that all theories on the origin of everything, life, the moon, the sun, everything, are all pure speculation. If you believe the moon happened because of a collision, then it is exactly that, a belief, a religion in a sense. There is no escape from belief other than first hand absolute observation. Also, if there is a God that created everything, would not all of his creation and the scientific laws therein point toward him? also, if I may reference the aforementioned dictionary.com: the definition of science is "The OBSERVATION, identification, description, experimental investigation, and theoretical explanation of phenomena. " Therefore, if you follow my logic, then what you are discussing here is NOT SCIENCE, it is RELIGION. please, leave your anti-creation bias out of all speculation of origins and include the "creationist" standpoint. Mind you, there doesn't need to be a slant either way. Remember, the foundations of science are built on a diversity of theories. 209.195.175.11717:14, 27 January 2006 (UTC)
If you read the section in question you'll see that the collision theory is based on observation (geology of the Moon). In contrast, the "creationist" explanation is based on authority (the Bible). So, I think it's clear which one can be called the more scientific theory. Awolf00218:39, 27 January 2006 (UTC)
My argument has been misheard. Please, let me rephrase. I was by no means saying the creation standpoint is RIGHT. I'm simply saying it is a possibility. However, the creator of this discussion and many others have seen it fit to exclude it from even possibility. I'm simply saying that even representation should be advised. The bible is also speculation. Now, I've said my peace and I don't believe I have enough resources or knowledge of FACTS (note the argument on moon dust, which has been a heated debate over the age of the moon and has been discredited and recredited so many times I can't count it.) Current evidence can point both ways, please show both ways.209.195.175.11723:10, 6 February 2006 (UTC)
IMHO, there simply is no point in including Creationist viewpoints into a scientific article. Creationism is per definitionem non-scientific, because scientific hypotheses must a) allow predictions and b) be falsifiable. Now, would you dare to make a prediction about God's future behaviour? Or how would you disprove the existence of a God? You can't, because an almighty God could always set things up to make it look like he isn't there. (The question why he should play such a stupid game is... well.) Thus, religious topics are not within the range of scientific discussion, and vice versa.
Perhaps more to the point, the statement "God may have created the moon" doesn't make sense at all, because in every Christians POV God created the whole universe anyway, thus you'd have to add this sentence at the end of each and everything. In how far God endowed the universe with the laws of science to run down its path of evolution like a clockwork, and in how far he resorts to "miracles" (skipping his own set of rules, for some obscure reason) to create a moon which is not compatible with science, is a matter of discussion. So, the statement in question could more meaningfully be rephrased as: "Some think the existence of the moon is so strange, it requires a miracle to explain it." If you want to. --Syzygy11:24, 20 February 2006 (UTC)
Double planet reference in 'Orbit'
Yet more howling at the Moon. The second last paragraph of the Orbit section started with the sentence The Earth and the Moon form in fact a "binary planet": each one is more closely tied to the Sun than to the other. I have removed it for two reasons:
It was completely unrelated to the rest of the paragraph; I hesitate to say "bad style", not being in a position of authority on this sort of thing,
Much more importantly, however, is that it was a flagrant misrepresentation of the dynamics of the Earth/Moon/Sun system. The fact that the Sun exerts a quantitatively larger force on the Moon than the Earth does is not particularly important, since the Sun also exerts a similarly large force on the Earth as well. It is not the direct Sun<->Moon and Sun<->Earth forces that matter, but their differences, or, in dynamics-speak the 'tidal potential': the Moon orbits the Earth (not the Sun) because the tidal potential due to the Sun is much smaller than the potential that binds the Moon to the Earth. Or, to come back to the edit, if the Earth and Moon are in fact a "double planet", it is not because of the absolute value of the forces due to the Sun on either body. mdf17:37, 9 August 2005 (UTC)
Nineteen year cycle
I was talking with an astronomer on the night of the 28th-29th of August who stated that the moon in the UK was at its most northerly point, an event that happens only every nineteen years. Can anyone here verify this or offer a reference to further information. Thanks - Solar18:11, 31 August 2005 (UTC)
The "Earth-Moon" images clashed badly on my computer (Firefox, 1280px wide screen, Bitstream Vera Sans font, Classic skin), so I tried unclashing them. This eventually led to putting the six images in a float:right table as a group. I also put the Moon photo above this section in a one-cell table of its own and put a br clear=right above this section. Please check this works in all reasonable setups on your own screens and correct as needed - David Gerard11:34, 29 September 2005 (UTC)
Those images seem to be pretty poor quality for a prominent article like the moon - to start with they are jpeg when they should be png (artifacts are clearly evident), images 4,5 and 6 are effectively meaningless (they add nothing to the text explanations), they are difficult to follow, and are badly drawn. I'd support scrapping them - in fact I might just try and work on a replacement with just one or two images. StuartH10:15, 29 October 2005 (UTC)
The artifacts are largely on the inside, so they're not too disturbing, but drawings should indeed not be jpeg's - and anyway, a combination of small images and heavy compression is always a bad idea with jpeg; just 5kB per image is ridiculous. Image 5 indeed doesn't clarify the story for me. And I understand what image 4 means, but only because I understand the text, I suppose. Also, I don't see (with or without image) how the magnetic field could be affected.
I removed the following from the end of the 'Exploration' section:
For escaping at the surface of the Moon from the Moon and the Earth, the escape velocity is the square root of the sum of the squares of the separate escape velocities of 2.4 and 1.5 km/s, or 2.8 km/s. Thus, using the orbital speed of 1.1 km/s, a delta-v of 2.4 km/s, just enough for escaping the Moon, is more than enough to escape Earth as well.
I'm not entirely sure what is meant here, but is is written so badly I couldn't leave it. Does anyone understand what is meant here? DirkvdM06:18, 28 October 2005 (UTC)
Future of the moon
Should we add a section about the future of the moon to this page? I believe the moon is currently receding from earth at about 3 cm per year due to tidal forces and transfer of angular momentum, but at some point this transfer would stop and the moon would stop receding.
I've also read, I believe in Astronomy or Sky and Telescope magazine, that the moon will then start approaching earth until tidal forces rip it apart and give earth a mighty saturn-like ring. Since we have theories about the origin and history in the article, we should probably address the future as well. --Fxer17:07, 1 November 2005 (UTC)
I like the idea of a Future of the Moon section, provided it doesn't become a haven for random crank theories. The first cut at it needs to be good, and cite very legitimate sources, so as to deter people from just adding in any old thing they heard from their parent's brother's cousin's friend's sister's ex-husband... ya know? The other danger would be speculations on if and how the Moon will be colonized, and that's not really appropriate for the article. Maybe "Scientific Future of the Moon" might be a better title... I gotta think this over. --Michael18:47, 1 November 2005 (UTC)
Why not make a colonisation section? That could then be combined with the 'legal status' and 'installations on the moon' sections (well, maybe not the latter). There has been quite some talk about the pros and cons of this (eg launching space missions from the Moon or mining). Leaving something out to prevent people adding nonsense would spell the end of Wikipedia as a whole :) . DirkvdM06:58, 2 November 2005 (UTC)
Sunset and Sunrise on the Moon
Hi Guys,
I have a question. Since the Moon doesn’t have an atmosphere (in earthly terms) how will the sunrise and sunset look like from the Moon? On Earth we can see twilight before dusk and after dawn and it gives us a feeling of a smooth transition stage from darkness to daylight and vice versa. As we know, twilight is due to diffusion of light through the Earth’s atmosphere. However on the Moon, this phenomenon cannot (possibly) happen. So, I guess, upon sunset the light will go off as if it were “switched off” and during sunrise, the light will appear as if a light source were switched on as soon as the Sun is visible on the horizon. Is this correct? Comments please?
Shibu Jacob, November 15, 2005
Light reflected off of any hills might cause some light past the local sunset/sunrise. Also, if on the Earth-facing side of the Moon, any light reflected off the Earth will provide some illumination. But yes, it would get a lot darker a lot sooner than on Earth. --Patteroast02:54, 16 November 2005 (UTC)
Thanks Patteroast for your explanation. One more doubt. Will it be possible to see the brightest stars (or other planets) from the Moon during day time, because the sky might appear dark? SJ Nov 17, 2005
Tony Dunn, Jan 25, 2006
The Sun moves across the Lunar sky about 12 degrees per day, or about 1/2 degree per hour. Since the Sun is about 1/2 degree wide from the Moon, an hour will pass from the time the Sun first touches the horizon, or mountain or whatever it will set behind, to the time the solar disk completely vanishes. So it won't be like an instant switch. Then, as was said earlier, it will take another few hours for the corona to set, and for the peaks mountains to the East of you to experience sunset. So it will probably take a good 6-12 hours of day to fade to pitch black, ignoring Earthshine and light from the stars.
Thanks Tony Dunn, for your informative explanation...!! I did not imagine (even though I should had..!!) that the movement of solar disk across the lunar sky is only 12 degrees per day. While posting this question, I thought Solar disk moves as fast as we see it moves from Earth, behind horizon. Is it possible to add this information in the main artile (for common readers).
Or rather, has anyone ever doubted it since the beginning of civilization? I ask because in Scientific understanding, we have
By the Middle Ages, before the invention of the telescope, more and more people began to recognize the Moon as a sphere, though they believed that it was "perfectly smooth".
That strongly implies that this was some sort of medieval discovery. The news would surprise Aristotle, who kenw it was no more flat than the Earth. If nobody pipes up soon with a plausible explanation, I'll fix this detail.
Dandrake02:27, 11 December 2005 (UTC)
I agree with your argument. Considering that nobody educated in the Middle Ages believed the moon to be flat, this paragraph is misleading. A clarifying sentence that at least since Aristotle the moon (as the other planets and the sun) was thought to be perfect spheres would be a good addition. Bhaak09:05, 12 December 2005 (UTC)
Perihelion??
Interestingly, the abnormal orbit of the moon had delayed the formulation of Kepler's Laws. Upon observing intricate measurements of the moon's orbit, Kepler discovered inconsistencies in the moon's perihelion. Scientists still cannot the apparent lack of consistency between the orbit of the moon and other satillites in the solar system.
Removed this section, since it does not make any sense to me. Can anyone explain what this is supposed to convey and if it can be sourced/verified? Awolf00202:26, 16 December 2005 (UTC)
Energy and momentum transfers - incorrect?
The paragraphs that start "The energy loss of the Earth's spin" and "Since both angular momentum and energy are conserved" are incorrect, in my opinion. For example, why must there be "a mechanism on earth to store a surplus or a deficit of angular momentum"? The transfer of angular momentum from the earth to the moon would happen just the same even if the Earth (apart from its oceans) were a cold solid lump of non-magnetic material with no magnetic field and no internal material currents. Occultations13:45, 22 December 2005 (UTC)
Agreed. E. g. we could assume that Earth deformes completely elastially, i. e. no friction losses. Then there would still be a certain loss in rotational energy due to slowing down. The moon would take all of the angular momentum but only part of the energy, as it has to be acording to well-known physical laws. So there would still remain some non-rotational energy at Earth, and it would namely consist of waves created by the tidal bulge. 193.171.121.3021:27, 9 February 2006 (UTC)
Birth Of The Moon
It seems to me that this book and his author are not part of the set of creators of peer-reviewed theories about the origin of the Moon. Instead, this seems to be a non-notable book with unorthodox (to say the least, with dinosaurs roaming the Moon's surface [2]) speculations. I remove it from the Origin's section until proven otherwise Awolf00218:16, 24 December 2005 (UTC)
Halt in Lunar Exploration
I'm not sure if this is important, but I know about a whole pack of conspiracy theories concerning the allegedly "inexplicable" halt of manned missions to the Moon after the 70-s. There is little to none mention of this in the article itself, which leaves the reader familiar with these theories puzzled. I realize not every conspiracy nut has to be presented in Wikipedia, yet the total blackout on this issue bothers me. Just putting it out there; thanks for your time.
There's nothing inexplicable about the cessation of manned missions to the Moon after the 70's. Putting a man on the Moon is hugely expensive, and America suffered a prolonged economic recession at the beginning of the 1980's; the Space Race was largely over. Future generations may wonder why we sent men to the Moon at all, considering that it is cheaper and just as effective to send robots there to do the same tasks.
The Nixon Administration cut NASA's funding. Forcing NASA to cancel Apollo program and cut thousands of jobs. People lost interest so funding was never restored.
There was actually a Fox TV program that aired concerning this. They gave a mass amount of proof that man never landed on the moon. I am a huge NASA fan but now I believe that they did not land on the moon.
Nick
Terminology, please - they gave a large amount of evidence. Proof would be, I dunno, firing a laser up at the moon and not getting a reflection. --Golbez04:19, 15 March 2006 (UTC)
Crust composition
The table gives the crust composition in percent but doesn't mention if it is in percent of mass or in percent of atoms. Which is it? The Infidel12:19, 22 January 2006 (UTC)
Is that a geological tendancy? I did a quick check and while units like ppm can be by weight, they're more often by mol. Also, ~40% oxygen would seem far more likely to be a molar, rather than mass-based, measurement. — LomnTalk22:02, 21 February 2006 (UTC)
I think that's a deficiency in the article. Elemental percentages might be some astronomical convention that I don't know about. When I look at other articles [3] they specifically state 'wt.%' of Fe0, etc. This is the usual convention with minerals. --Zeizmic22:15, 21 February 2006 (UTC)
So that is quite like it looks to me: generally those compositions (on earth!) are measured by wight, but ometimes in mol. When elements are recognized by spectroscopy or calculated from nuclear processed, it's probably mol, not weight, unless the numbers are converted to match the supposed usual measure. All in all, we don't know for sure.
Thomas J. Ahrens (ed.), Global Earth Physics : A Handbook of Physical Constants, American Geophysical Union (1995). ISBN0875908519 Composition of the Solar System, Planets, Meteorites, and Major Terrestrial Reservoirs, Horton E. Newsom. TABLE 11, Compositions of the Silicate Portion of the Moon. From these sources:
A: Anders, E., Chemical compositions of the Moon, Earth, and eucrite parent body, Phil. Trans. Roy. Soc. A285, 23-40, 1977.
D: Jones, J.H., and J.W. Delano, A three component model for the bulk composition of the Moon, Geochim Cosmochim. Acta, 53, 513-528, 1989.
O: O'Neill, H.St.C., The origin of the Moon and the early history of the Earth - A chemical model. Part 1: The Moon, Geochim. Cosmochim. Acta, 55, 1,135-1,157, 1991.
T: Taylor, S.R., Planetary Science: A Lunar Perspective, 481 pp., Lunar and Planetary Inst., Houston, 1982.
W: Wänke, H., H. Palme, H. Baddenhausen, H. Kruse, and B. Spettel, Element correlations and the bulk composition of the Moon, Phil. Trans. Roy. Soc., A285, 41-48, 1977.
R: Ringwood, A.E., S. Seifert, and H. Wänke, A komatiite component in Apollo 16 highland breccias: implications for the nickel-cobalt systematics and bulk composition of the Moon, Earth and Planetary Science Letters, 81, 105-117, 1986.
Though this source also uses the ambiguous ppm notation, from comparing the data for the Earth with other sources (CRC, Kaye&Laby, Greenwood) that explicitly state the units, it's evident that this means mass fraction.
A cutoff value of 0.1% should be good enough as an overview. "<" stands for small values that I didn't bother to copy (they're available down to the ppb range). Note that they're all estimates based on various assumptions. For the infobox, I arbitrarily chose the most recent source, O'Neill, with the oxygen value from Wänke. I also updated the similar table (also without apparent references) at Geology of the Moon.
Hi. The compositional data table in the article is labelled "Crust Composition", when in fact it is the composition of the crust plus the composition of the mantle. This is a non-trivial distinction. In geochemical circles this would be called the "bulk silicate" portion of the moon, or just the "silicate" portion because it is the average composition of the entire moon, minus the core (which is dominated by Fe-Ni, not silicates). I don't know what label would be most clear. Correct labels include "Bulk composition of crust and mantle", "Bulk composition of the silicate portion of the moon", "Bulk composition of the moon minus the core". Or a more pleasantly worded version thereof...my writing is not nearly as poetic as others here. :) If it helps any, the table in O'Neill's paper that these values are presumably taken from (I haven't recalculated them myself to check) is called "Composition of the Moon (silicate portion)...". Rickert21:04, 6 March 2006 (UTC)
Sure, anybody, relabel and describe as appropriate! (Though don't come to me for poetic writing, either.) I'm not an expert on geology, my primary concern was to put some sort of citation behind numbers that were lacking verifiability. Femto21:47, 6 March 2006 (UTC)
Done. I just wanted to see if anyone had a clearer way of labeling the table. Not everyone immediately understands what is meant by "bulk silicate moon", although it is probably the most precise title... Rickert22:03, 6 March 2006 (UTC)
lead image
Maybe it's just me but I like the older one (on the left) better
The second seems much darker, although it has the advantage of being a completely full moon, the first one seems about 1 (1/2?) day or so away from full. I also like that it doesn't COMPLETELY fill the box, a little black all the way around is better, IMHO. I just started watching this article beacuse of the vandalism so I have no background on which is really better, sorry if this got talked about already but did want to mention it. ++Lar: t/c00:27, 29 January 2006 (UTC)
Don't forget to license-tag it correctly, right now it's tagged for deletion. Since you started with a PD source (a NASA image), I suggest something like {{GFDL-self}}. I'd also suggest that instead of brightening the 250px image, you brighten the original assuming your photoshop can handle it (may be memory intensive!). mediaWike will automatically generate a 250px version of that image the first time it's rendered in an article so there's little space/bandwidth savings to be had by only doing the small one... In any case thanks for your efforts!!! ++Lar: t/c22:47, 4 February 2006 (UTC)
I disagree with this being a good picture. It is made from pictures taken by a Moon orbiter (I think Clementine) and you can actually see the seams between the individual images. This is too far away from reality to be used as a replacement. Awolf00200:42, 7 February 2006 (UTC)
You can see the seams at in the full original image, but not in the 250px version. However the currently used image is at Featured Picture status so maybe my idea that there are better ones is wrong. ++Lar: t/c00:57, 7 February 2006 (UTC)
The Clementine pictures are cool, but I have to say I prefer the original image as well. Not being full is a plus for me, since I think it helps highlight some of the surface detail. Actually even beyond that the original picture seems to have more texture than the Clementine one. I like them both, but I think the original one should stay. — Knowledge Seekerদ01:48, 7 February 2006 (UTC)
Tidal Forces
I came in through the link to the talk page about the factual nature of the information on the tidal forces. I couldn't find it, so here's what I have to say:
It should be mentioned that the tides on Earth on not due solely to the moon. The sun causes tidal bulges as well. Thus the moon either increases the bulges or balances out the bulges, depending on its location orbiting Earth.
While reading the article on the moon, I noticed that it mentioned in the Tidal Forces section that the tides are influenced mostly by the moon, and very little by the sun. However, this is exactly opposite of the actual relationship. This can be proved with physics.
Consider that the force of gravity on a celestial body can be shown by Fg=[G(M1)(M2)]/R² , where G is the gravitational constant, 6.673x10^-11, M1 and M2 are the masses of the objects involved in Kilograms, and R is the Orbital Radius, or the average distance between the centers of the two masses in meters.
The earth's mass is 5.97x10^24 Kilograms, the mass of the moon is 7.35x10^22 Kilograms, and the mass of the Sun is 1.99x10^30 Kilograms. The orbital radius of the earth about the sun is 1.50x10^11 meters, and the moon about the earth is 3.84x10^8 meters. All of the above figures are according to the NASA Jet Propulsion Laboratory Solar System Dynamics Group (http://ssd.jpl.nasa.gov).
According to Newton's Laws, the force of gravity from a first object on a second is equal to the force of gravity exerted on the first object by the second. Therefore, the moon has an equal pull on the earth as the earth does on it, and the same is true of the earth and the sun.
By calculating [G(M1)(M2)]/R² for each mass and distance relationship, one may observe that the force of gravity of the sun on the earth is 3.523432973x10^22 Newtons, and the force of gravity of the moon on the earth is only 1.985730682x10^20 Newtons. Therefore, the ratio of the gravitational force of the moon to the force of the sun is 5.6357839x10^-3:1, or the moon has roughly 0.56% of the force on the earth as the sun has.
The claim that the moon has a more prominent effect on the tides than the sun is therefore preposterous; compared to the impact from the force of the sun, the moon comparatively makes mere ripples in the water. I hope this clarifies this issue.
Actually, the computations are not done corectly. The force of gravity of the sun on the earth is 4.354x10^20 Newton (plural is not used!), and the force of gravity of the moon on the earth is 1.98x10^20 Newton. Therefore, the ratio of the gravitational force of the moon to the force of the sun is 2.19. (if you make the same computation for Venus, for instance, it will give 0,00014x10^20 Newton).
The combined force is 2,374 Newton during full moon and 6,334 Newton during new moon (acting in the direction of the sun), and 4,783 Newton during quarters (acting in a direction deviated from the direction of sun by 24º). But, due to the differencial effect, the tidal action of the Moon and Sun during full moon add to one another - so, for tides, it is as if the force was also 6,334 Newton).
So it is clear that the tides are influenced by the combined atraction of the sun and moon. The sun is the main actor. The Moon adds to the effect - increasing it by 45% - during full and new phase (causing «spring» tides), and decreases the effect by 25% and shifts it in time (by one hour, 24º/360º or 24º/24h) during quarters.
Tidal acceleration is not the same as gravitational acceleration. You can't compute it as simple force on the center of masses. See tide or tidal force. Femto14:59, 7 March 2006 (UTC)
I will take a look at that..and get back to you later... Anyway, I must apologize because the numbers I wrote about «forces of gravity» were the ones corresponding to the forces on the Moon by the Earth and Sun. The atraction of the sun on the moon is 2.19 times the Earth's atraction on the moon! But that is not relevant to our discussion! Sorry. (I had made these calculations for another problem and did not realize my mistake!)
So finally I agree! Now I understand that what is revelant is not the fact that the gravitation force from the Sun is 179 times the one of the Moon: 3.54*1022 N vs. 1,98*1020 N.
(And not 2 times!, as I wrote before... what is true is that the gravitation force from the Sun is 2 times the one of the Earth over the Moon!... 4,35*1020 N vs.1,98*1020 N)
What is relevant is the difference in gravitation force on the two sides of the Earth, which is what causes the unbalance leading to tides. Using the formula in tidal forces, we see that we have to multiply the gravitation force values by a factor (Earth radius/Distance). So for the case of the Sun, we have 4.26*10-5=6.38*106/1.5+1011, and for the moon, 1.66*10-2=6.38*106/3.84+108... And so, in fact the final values for the tidal forces are: for the Sun, 1,51*1018; for the moon, 3,29*1018. The influence of the Sun is 45,9% the one of the Moon!
I apologize again for my mistake. I had never before thought more deeply about this subject... and my irrelevant calculations lead me to an error! (but you always learn a lot when you correct your errors... and it is a lot of fun!)
You explain this basic but common misconception yourself better than I could have done. - That cleared up, there also seemed to be no reason left on this talk page that would justify keeping the legacy 'disputed' tag in the Tidal effects section. (removed) Femto21:47, 7 March 2006 (UTC)
I aggree. I made a slight change in my text of yesterday to make the exponential factors more readable and to change the word «pull», that I used, for gravitational force, as the term «pull» is not correct because it gives the idea of movement.
The process of Earth's day lengthening and Moon's distance increaseing will stop when 1 future Earth day = 1 future Earth month ~ 55 current Earth days. The Moon will can never be seen from a hemisphere of Earth and suspend on a fix position when be seen from the other hemisphere. -- G.S.K.Lee15:27, 3 March 2006 (UTC)
The effects of the moon many millions of years ago, must have been quite different than they are now, not only how it influenced the weather, but also how tides (not just ocean tides) affected things. Any comments or links to such information would be nice.
I'm still mulling this over after it was inserted. I find the section misleading, since the Moon does orbit the Earth (which orbits the Sun), even if the layout of the orbit might look like stated in this section. And the argument about the strength of the force exerted by the Sun does not come into play in this, just the escape velocity of an object in the Earth's gravity well, I think... Awolf00219:29, 14 March 2006 (UTC)
I used a very provocative title, I know... If the Wikicommunity wants to change it, it's ok with me. But I think that the subject is in fact relevant. It is almost as geocentric to say that the Moon is orbiting the Earth as it is to say that the Sun is moving around the Earth. Both of them are lies, for any less geocentric frame of reference. Actually, the Moon and Earth travel together around the Sun. And they both do a «pas de deux» ballet number together, rotating very very very slowly about their common center of mass, as they follow their common orbit around the Sun. We tend to think that the rotation is more relevant because we see the Moon daily rotating around the Earth. But actually it is just «a small detail».Tó campos21:54, 14 March 2006 (UTC)
But if its period were faster, its path would overlap. The moon orbits the earth, the earth orbits the moon, the Earth-moon system orbits the Sun, the Sun orbits the Earth-moon system, but I would not say the Moon orbits the Sun just because it happens to create a diagram that makes it look like it. --Golbez22:18, 14 March 2006 (UTC)
I did some minor chages to make the article less provocative. What do you think about it now? --- It is not only a diagram that makes it look like the Moon is orbiting the Sun. If the Earth suddenly disappeared, the Moon would continue orbiting the Sun. The presence of the Earth just makes it describe a very slighly different orbit. It goes against common sence, but is that important? Should we discard Modern Physics because it goes against common sence?Tó campos23:38, 14 March 2006 (UTC)
What do you mean by "Modern Physics"? This motion is well described with classical physics since Newton's time, and it seems to me that it says the Moon is in a closed orbit around the Earth, just as any other "captured" object in the Earth's gravity well. I do not understand your problem with this statement. Awolf00214:23, 15 March 2006 (UTC)
I just talked about Modern Physics to comment that, for instance, general relativity and quantum mecanics also imply a vison of reality that go agaisn't common sense. Please take a look at the references I included as links. I think that they make it all very clear. The moon has a heliocentric orbit. It also orbits the Earth, and as the Earth orbits the Sun, the moon orbits the Sun. The planets' orbits are ellipses. The moons' orbits (around the Sun) average out to be the same ellipses.Tó campos15:58, 15 March 2006 (UTC)
Well, I just don't see the value of this 'exercise'. Just because the orbit is convex at all times (geometric argument) the text (and the references) make conclusions about the binding of an object to another in a gravity field (energetic argument), it seems. This is not helpful at all in a multi-body situation, IMO! What am I missing? Awolf00216:21, 15 March 2006 (UTC)
The title alone is a misrepresentation: the Moon is in a geocentric orbit of the Earth, subject to perturbations by the Sun. Every single model of the motion of the Moon -- from Newton, to Hills, and even latest numerical integrations from the JPL begin with this basic fact. Indeed, assuming it was in a heliocentric orbit would add a nasty set of complications to these models, a kind of latter day Ptolemaic system. If the section remains, the simple energy argument mentioned above should be stated. The fact that the actual trajectory of the Moon is convex with respect to the galactic centre (or whatever reference frame is chosen) isn't particularly important. However, I suspect that section really needs to go completely. I'm within an yoctometre of zapping it myself. mdf00:26, 21 March 2006 (UTC)
In spite of what Newton said and JPL numerical integrations seem to imply, I still think that it is more correct to say that the Moon is in a heliocentric orbit of the Sun, subject to perturbations by the Earth, that accelerates and retards its movement. If the Earth suddenly disappeared, the Moon would keep basically the same orbit about the Sun. From the point of view of «an engineer» the geocentric model is more useful and should be used, because it is simpler. But in fact I think that Galileo Galilei would agree with me that it is the geocentric model that should be compared to the geocentric Ptolemaic system. And I think it is interesting for most persons to realize what the real trajectory of the moon looks like, anyway. But if the majority of enciclopedians think it is better to zap it, go ahead if you like. (Provided you don't send me to the Inquisition for holding the idea that, as the Moon moves, it is the Sun that stands «still» at the center.... Ah ah ah!) Tó campos12:32, 21 March 2006 (UTC)
This argument of 'disappearance' is proving nothing, IMO. If the Sun disappeared the Moon would still circle the Earth, just as well. To illustrate the "binding" argument from the energy point of view, think of a single ionized atom, say Xenon, in a magnetic field. Are the remaining electrons in the atom circling the magnetic field lines or the nucleus? Awolf00215:58, 21 March 2006 (UTC)
I still have the same opinion and thought it would be interesting to keep this section, though it could be somehow modified by one of you. (I just read for the first time the french Wiki-article on the Moon orbit and it says "One can regard the Earth and the Moon as a double planet, the gravitational influence of the Sun being comparable with their mutual interaction.") But, as it seems I am alone in my position here... No problem! Maybe you are right and it is a point of view that is not interesting to the majority. I will keep it to myself. Tó campos17:59, 21 March 2006 (UTC)
I removed it, but I still think some of it might have a place. The diagram showing the orbit might be useful. However, I stand by my previous comment. The Moon orbits the Earth, and vice-versa; and the Earth-Moon system orbits the Sun, and vice-versa. Likewise, Deimos and Phobos orbit Mars, and vice versa, and the Mars-Deimos-Phobos system orbits the Sun, and vice versa. IANAPhysicist, but I don't think you can't really separate the bits out when dealing with this. --Golbez19:42, 21 March 2006 (UTC)
I liked it, and thought it was good science. Why don't we rewrite it slightly and put it back in there? Guinnog19:49, 21 March 2006 (UTC)
The bit about the moon's path round the sun being like a motorcycle. I've never understood it before. Of course, it all depends on your viewpoint. From the Earth it does one thing, if you were standing on the Sun another. Guinnog21:23, 21 March 2006 (UTC)
I disagree. The moon's true path in space relative to the sun is a pretty important bit of science in an article about the moon, I would say. Guinnog22:31, 21 March 2006 (UTC)
Why? What makes it good science? What about the "true path" is *important*? What changed in science and physics after we realized that? I said, you can probably find a place for the image and a short blurb, "Look! When looked at this way, it kinda looks like the moon is orbiting the sun!" but certainly not the large treatment it got before, implying that it only orbits the sun. --Golbez22:35, 21 March 2006 (UTC)
If you don't realise why the true path of a body is important in an article about that body, I cannot explain it to you. As for the tone, I mentioned a rewrite. But there were bits of that that are worth keeping, in my opinion. Guinnog00:29, 22 March 2006 (UTC)
Pedantry will get you nowhere. The "true path" is like that only because its period is so slow. If it had a period of 12 hours, it would look, well, like a moon orbiting a planet. Just because its period is slower doesn't mean it doesn't orbit the Earth. It's trivia at best, and a pretty diagram that makes you go "huh". It doesn't change the fact that, uh, it orbits the Earth, and is tidally locked with the Earth. --Golbez00:45, 22 March 2006 (UTC)
If you can't explain why it's important on this talk-page, why are you sure you can do it in the article? And even if you could (somehow) do it there (but not here), standard wikipedia policy on original research would likely force its removal anyways -- unless you can cite a reputable source on these matters. mdf01:02, 22 March 2006 (UTC)
There is nothing of original research in this. Check Orbits- Particle Physics and Astronomy Research Council -Royal Greenwich Observatorywhere you can read the following: «The Moon is the closest astronomical object to the Earth. With the Earth, it forms what is almost a double planet, for no other planet has a satellite that is as large in comparison to the size of the planet.» «The orbit of the Moon is especially complex because the pull of the Earth and that of the Sun are not too dissimilar.
It is a surprise to many that the path of the Moon about the Sun is always curved in the same way, concave towards the Sun, and is nowhere looped or even convex towards the Sun. This despite the fact that we know that is is orbiting the Earth each month. » It is because that is surprise to many that it could be interesting to talk about it. The Royal Greenwich Observatory thinks so... You can check also The College Mathematics JournalTó campos 1:44, 22 March 2006 (UTC)
"Information Leaflet No. 51" from the RGO doesn't strike me as being a peer-reviewed publication of research. But that's just a distraction: the issue at hand is whether or not the convexity of the trajectory with respect to George Bush's navel (pick another frame of reference) is important, and your source does not address this question. It just cites it as a piece of trivia, like many others. Your second reference appears to be a letter to the editor of some journal. Even if we can't dismiss this as non-research (almost by definition), it simply explains why the orbit is convex -- both with respect to the Sun and GWB's bellybutton. Where is the importance of this fact discussed, and substantive use of it made? At least beyond its pedagogical use for first year physics or math courses. mdf02:41, 22 March 2006 (UTC)
I don't see where anybody's navel comes into it. It is important that our closest astronomical companion follows a certain path around the sun with us. Guinnog07:21, 22 March 2006 (UTC)
I am new in the Wikipedia... but I am very surprized by all this emotional dispute.... In 1974, the book «Principles of Astronomy» by Stanley Wyatt used in most US universities already presented this estabished fact. And I think it is important to show that our Moon is not an ordinary sattelite. It is a satellite that is unusually large in comparison to the size of the planet and suffers a pull from the Sun that is 2.2 times larger than the one of the planet. It is 50% larger than Pluto and has a mass which is 5.5 times bigger. (Only Pluto has a larger satellite than the Earth... but that is why astronomers talk about Pluto and Charon as a binary planet.)
Which is why I've been saying that the Moon orbits the Earth, the Earth orbits the Moon (but in a far less pronounced fashion); and the Earth-Moon system orbits the Sun, and the Sun orbits the Earth-Moon system (but in a far, far less pronounced fashion). Gravity and orbits are a two-way street. But that doesn't mean the Moon orbits the Sun. The Moon is part of a gravitational system that does. This is the way it is with all satellites. --Golbez17:12, 22 March 2006 (UTC)
In 1974 the claim of "unusually large" could be made ... but in 2006 this is no longer the case, since we now know of Pluto-Charon and some asteroids. The business of the force due to the Sun is a pointless distraction ... unless one is willing to ignore (at one's peril) the similarly large force the Sun exerts on the Earth. As mentioned above and elsewhere, the business of the convexity of the trajectory about the Sun is also irrelevant. Dynamics tell us the Moon is in a perturbed geocentric orbit. Since Newton, every single model of the motion of the Moon accepts this as an axiom. If any facts about its motion need to be mentioned it is the ones I've just spoken. If any graphics of the Moon's motion need to be displayed, they should reflect the complexity of its motion in the geocentric (or even Earth-Moon barycentric) frame -- it isn't even close to being closed, it wiggles and wobbles, oscillates, stretches and so on. Referring the motion to the heliocentre or the solar system barycentre or the cash register at the local Tim Hortons just adds a huge complication dynamically speaking on top of the almost unspeakably difficult geocentric case (Isaac Newton is reported to have said that the problem of the motion of the Moon "made [his] head ache"; late 19th century models (Hill, Brown, et al) were nasty, brutal, affairs, hardly even amenable to computer implementation today -- indeed, despite the truly awesome human-powered computational and analytical tenacity that went into them, they are more or less historical curiosities these days since everyone now uses the JPL ephemerides). For all of these reasons, I (and perhaps others) are truly surprised to see claims about enhanced pedagogy, etc, regarding these matters: the problem is not simple, making it more complicated can't improve matters, and speaking things that are in direct contradiction to observed physical reality does no one any good. mdf19:47, 22 March 2006 (UTC)
Of course the Moon is safely within the gravitational sphere of influence of Earth and so its orbit is not independent of the one of the Earth. And of course the Moon is in a perturbed geocentric orbit. But it is also in a heliocentric orbit (which, of course, is not independent of the one of the Earth). The orbit of every planet and moon are very complicated. But the orbit of the Moon is especially complex because the combined gravitational «pull» of the Earth and Sun (2.2 larger) is always directed towards the Sun (oscilating about + and - 24,45º during each month -» + or - arctan(1/2.2)) and not directed towards the Earth. And so the orbit of the Moon in terms of a referential centered in the Sun looks very similar to the one of the Earth. Geometrically, it all works as if the «center of curvature» of the trajectory oscilated slightly around the real position of the Sun during each lunar month. This is unusual and worth mentioning. Tó campos12:44, 23 March 2006 (UTC)
You keep bringing up this "the Sun's force is 2.2x larger than the Earth's"; it is a complete red-herring. It has no dynamical significance. Your claim that the "combined gravitational pull of the Earth and Sun" is "always directed towards the Sun" is only true if you fail to subtract the force the Sun "pulls" on the Earth itself. This has been pointed out many times now, and you continue to repeat it. Why do you persist in this error?
Your further claim that the centre of curvature of the Moon's trajectory about the Sun oscillate[s] slightly about the real position of the Sun is also completely false, as you can see by the graphics I have attached. In fact, I hestitate to show these graphics because this "centre of curvature" has no physical significance. But even if it somehow did have such importance, we can see that by the standard you are setting up, the Moon clearly orbits the Earth.
So, fundamental dynamics says the Moon doesn't orbit the Sun. Your proposal says the Moon doesn't orbit the Sun. Can we finally conclude that the Moon doesn't orbit the Sun, or will all this be ignored again and the "2.2x stronger" irrelevancy will be re-uttered? mdf18:59, 24 March 2006 (UTC)
Ok... I admit that when I wrote that the center of curvature of the Moon's trajectory oscillates slightly I was careless in the choice of the word «slightly»... (and I did not write that in the article....of course... I said it «in the heat» of the debate...)
But please notice that I never said that the Moon does not follow a geocentric orbit about the Earth! I am calling the attention to the shape of the Moon's track around the Sun and comparing it to the Earth's. The fact that the pull of the Earth and that of the Sun are not too dissimilar explains their similitude. The fact that the "gravitational pull of the Sun is larger", in Newtonian terms, "does not affect dynamics"; but it implies that it has a great influence in defining the geodesic of the Moon's free fall. The space-time curvature imposed by the Earth as it moves along is not enough to «cancel» the one imposed by the Sun. (Speaking in Newtonian terms, the combined Sun-Earth "pull" is the centripetal force that keeps the Moon moving in its trajectory, perpendicularly to its direction.)
If we "subtract the force the Sun "pulls" on the Earth", we are ignoring its effect in the definition of the geodesics; we are thinking in terms of a referential on Earth. Which is all right, if that is what we want to do. But of course the purpose of my presentation is to talk about the shape of the Moon's path in terms of a referential in the Sun. My approach would only be completely erroneous if my purpose was to talk about the geocentric orbit of the Moon. But that matter is already very well addressed in the main article. I am talking about Moon's path around the Sun and comparing it to the Earth's. And its shape is a surprise to many. Only that!
Am I persisting in an error? I don't believe so. I think that you are drawing wrong inferences from what I wrote. Maybe the problem arises because in this talk page I used the expression "the Moon orbits the Sun" (I did it in the article at first but I decided to change that for clearness). I use the word "orbit" with the meaning of "one complete passage around a body" (Oxford Dictionary). You seem to use it with a meaning that implies that the Moon is either orbiting the Earth or the Sun, but not both.
Maybe if I had always talked about "the track of the Moon as it moves with the Earth around the Sun" you would not express such dispproval. Can that be the problem? Tó campos 1:29, 25 March 2006 (UTC)
The section I introduced tried to explain why it a surprise to many that the path of the Moon about the Sun is the way it is (misleading representations in scholar books, lack of knowledge by school teachers...). And I think the Wikipedia could have an important role in eliminating that lack of knowledge about this estabished fact. Maybe we should «cool down the emotive dispute» about this and let astronomers and teachers decide if this information is important and relevant or not... Let's find a clearly recognized atronomer and ask him. What do you think about that way of solving the problem? Tó campos12:44, 22 March 2006 (UTC)
Earth&Moon's concave path around the Sun seems to go well in section Double-planet hypothesis. Like that, at least we can contribute to change the wrong idea comming from misleading representations. What do you think? Tó campos15:59, 22 March 2006 (UTC)
Period of Orbit
This is for clarity. The first sentence ("The Moon makes a complete orbit about the Earth approximately once every 29.5 days.") is contradicted by the "Revolution Period" figure in the table and is qualified by the second paragraph in a way that makes it inaccurate as a categorical statement, which it appears to be. I suggest deleting the first sentence and replacing it with the entire second paragraph which is an excellent, concise discussion that more completely and accurately answers the question, "how long does it take for a complete orbit?" Neev16:37, 9 April 2006 (UTC)
Poles of the moon
When viewed from earth the moon-rise on a full moon day, which are the north and south poles of the moon? - the sides on our left and right of the lunar disk or the the ones at top and bottom side of the lunar disk? For a common reader, who is not an expert on the subject "moon", this artile is missing with this type of minor points.
SJP April 20, 2006
I'm guessing this information is "missing" because the answer depends on where you are on Earth when you see the Moon rise... Awolf00218:20, 30 April 2006 (UTC)
But, moon will have poles, which are the points where its axis of rotation intersects with the surface... correct? SJP June 7, 2006
I think what he's asking for is a moon map - maybe the near side (moon) blank article referenced here could be started with this sort of info? Anyone got a PD picture of this as I get fed up trying to work out the tags to add to images! Sophia10:23, 7 June 2006 (UTC)
I think I can clarify things here. I hope I don't accidentally get too complex here. OK, The Moon DOES have poles, but not magnetic ones. On Earth, the magnetic poles and the geographical poles are different. The geographical pole is where the Earths axis around which it rotates exit the Earth. The magnetic poles are the uhhh...OK, well, I'm, not a magnetism expert, but you get the picture: the magnetic and geographical poles are different. :) So the Moon DOES have poles.
However, determining which one is which can be harded for people in different locations. If civilization had developed in the southern hemisphere, we would probably consider what is generally thought of as the "bottom" half of the Moon to be the "Top" half, because to look at the Moon, which orbits roughly around the Earths Equator (at a 5 degree tilt to the Ecliptic to be exact) from the northern, hemisphere, you have to look south, but to look at it in the southern hemisphere, you must look north, so it looks "upside down" (unless you sit upside down in a chair, or you have a strange disease that makes your head tilt funny).
If you didn't understand all that, then you don't have to. Just understand that if you're in the Northern hemisphere, the "north pole" is at the "top", and if you're in the south, the "north pole" is at the "bottom". :) The QBasicJedi20:57, 14 June 2006 (UTC)
Thanks QBasicJedi for your explanation. That makes sense. For those readers who did not understand QBsicJedi's detailed writing, I will simplify what I understood. "When you look at a crescent moon, the poles are at the intersections of the two arches made by the perimeter and the terminator. However, the way an observer see these points “up or down” depends on where he stands on earth and which direction he looks at the moon. On the equator, the crescent is not tilted to one side, rather it is in boat-shaped. When you observe further north or south of the equator, the tilt of the crescent increases, towards that direction. Therefore, a pole which "looks to be at the top of the crescent" will appear to be at "the bottom of the crescent" on the other hemispher of the earth because the tilt of the cresent reverses across the equator. Also, while the lunar disk "moves" in east-west direction during an earth-day in the celestial sphere the "top and bottom" of the lunar disk reverses in appearance.
I kinda figured it would be too complex. I try to simplify things, but I have a habit of going off on tangents. Oh well...
The QBasicJedi13:38, 17 July 2006 (UTC)
The web site you point to looks very confusing and unstructured. I do not think it can give any helpful information to a reader of this article. Awolf00214:08, 23 April 2006 (UTC)
In a total eclipse the moon is completely covered by the earth's shadow.
When the Moon moves into the Earth's shadow, the full Moon turns blood red. What makes it turn red is due to the light bent from the sun filtered by the earth's atmosphere.
The blood red color of the moon caused some ancient cultures to perceive total lunar eclipses as a kind of cosmic menstruation of the moon.
A "blood moon" is also noted in the Bible's Book of Revelations as a sign :from God that the book of seven seals had been opened as evidence that God's :wrath was upon man.
I think such a section is too short to give "Blood Red Moon" wider meaning in a reasonable way. Maybe it should have its own article or dab page? Awolf00223:58, 6 May 2006 (UTC)
I think so, I just saw a red moon outside but couldn't find an article on Wikipedia about it. - Rudykog09:24, 9 May 2006 (UTC)
Ancient ruins on the Moon controversy
To counter the usual "We never been to the Moon" case, there's been an alternative theory that believes that the forementioned conspiracy theory is simply a cover to deride people from finding out the "true" reason why we left the Moon (or told the public we stopped going, as John Lear states).
The scientific advisor for Coast to Coast AM, Richard C. Hoagland, frequently propounds and firmly believes that there are ancient ruins on the Moon and discounts the whole collision theory as a misinterpretation of the so-called hi-temperaturely formed "rocks" found when claims they're more akin to what would be found of New York in 10,000 years..
This prolly a whole lot of pseudoscience, as Phil Plait points out as here, but it should be noteworthy in its own way as they're been included other theories as the Welteislehre theory wherein which the Moon is made solidly of ice. DrWho4203:16, 30 May 2006 (UTC)
Facial Images on Moon
What is this? It looks NPOV, un-encyclopedic, doesn't site sources, and doesn't fit will with the article (it's like a 'pop culture references to the moon' type of section). I will be reviewing the history of this article to see if it's been around for a long time, but this section either needs to be put elsewhere or moved imo Piepants21:03, 21 June 2006 (UTC)Piepants
I have removed this, it is freshly added. It is not NPOV, it claims there are images on the moon, at least it should say "some claim to see...". A section on thigs people think they see in the moon would be more appropriate, there are probably many many things seen there over history. 213.103.205.11700:35, 22 June 2006 (UTC)
Removed twice by myself, user constantly re-adds, vandalism.
I reverted it thinking it was vandalistic section blanking, but now I see the section is obviously rather dubious, so remove at will. Everyking05:06, 22 June 2006 (UTC)
External links
I am not sure about the rules about adding external links but there is a software called VMA "Virtual Moon Atlas" available for free at http://astrosurf.com/avl/. This software offers an interface to navigate the moon, similar to Google Earth. It's quite better than the Google Moon listed already. It's quite efficient and very exhaustive and easy. I suggest we add it in the external link section. (from User dunwich)
The US is the only English-speaking country that doesn't use metric. Note also that the article uses the British word "torch" instead of the American "flashlight". So it's consistent as is. Plus it's a science article, about a feature located outside the US. thx113815:44, 9 August 2006 (UTC)
Query re Axial tilt
In the table, this article gives the axial tilt as 1.5424° to ecliptic (my emphasis).
However, see the article The_Moon's_Orbit, which states in the heading Inclination of the rotation axis, that the moon's axial tilt relative the lunar orbit is 1.5424°, but the axial tilt relative to the ecliptic is always 6.69° (as discovered by Cassini in 1721).Roo6012:46, 15 July 2006 (UTC)
It works for me on Firefox, however I also think that I really do not like it. In my oppinion this kind of animation adds nothing to the article. Awolf00221:13, 20 August 2006 (UTC)
It is a useful comparison between the size of the Earth and moon and their distance. I agree it is annoying, but should be kept and possibly be edited. Reywas9201:02, 21 August 2006 (UTC)
It doesn't fit on the page and it serves very little functional purpose on this page. There are better ways to illustrate the same concept (for example, rotating it 90 degrees would make it work a lot better). I've removed it for now—I'm sure you can find a better way to do this. If all it is meant to illustrate are the relative sizes and distance, this can surely be done a lot better without the distracting "speed of light" illustrated and without cutting the page off in funny ways. --Fastfission14:41, 24 August 2006 (UTC)
I placed it on speed of light. If anyone could perhaps edit the image so that it wouldn't move and the put it on Moon. Reywas9219:45, 25 August 2006 (UTC)
I may be wrong and probably am but that image depicting Alan Shepard on the moon.. can it be classed as a genuine photograph due to the image of the flag appearing to be flowing but the moons atmosphere has no air in which the flag can flow in. As i said i am probably wrong use know more than me so if you could let me know thanks
Don't worry about it, it's not a mistake by NASA conspirators! It looks like it's waving because 1) there's a pole in the top of the flag to make sure that it doesn't just slump in a rather unimpressive way 2) Shepard is shaking the flag pole as he plants it, making it ripple. Hope that helps you. Boyinabox17:43, 8 September 2006 (UTC)
