Talk:Moon

The statistics bar is somewhat confusing regarding the orbital inclination of the Moon's orbit. This confusion is cleared up with a good discussion about a third down the page, but it would be nicer if either a) it didn't cause the confusion in the first place, or b) it gave some hint that there was further discussion. See, the inclination is given with respect to the Earth's equator, like a normal satellite's, but if you follow the link to the Inclination page, it states "For the Moon however, the inclination is measured with respect to the ecliptic [...]". In light of that, I'm adding the inclination with respect to the ecliptic in above the inclination with respect to the Earth's equator. That's my solution, if other people have better solutions, they should implement them...

Aidan 03:51, 2004 Sep 1 (UTC)

'Energy from sunlight splits much of this water into its constituent elements hydrogen and oxygen, both of which usually fly off into space immediately.'

Why would this be ? The moon has Gravity and the molecules have some density that is higher than that of empty space! It should remain in some hight of atmosphere ?! Togo 05:01, 20 May 2004 (UTC)

The Moon has gravity, but not nearly as much gravity as a planet like Earth does; this means it has a lower escape velocity. As a result, the thermal motion of lightweight molecules such as oxygen and hydrogen easily reaches velocities higher than the Moon's escape velocity and the molecules never fall back to the surface. Bryan 05:11, 20 May 2004 (UTC)

Light falling on the Earth from the Moon is called "inlunation".

Never heard of that, nor can it be found on the Web.

Nor it can. I had back-formed it from insolation. So had a friend of mine with whom I was having a conversation. Anyway, thanks for deleting it. --drj

Actually, the correct term is "ashen light" ("lumière cendrée" in French), although that is also used to designate a faint glow occasionally observed on the dark side of Venus. Earthshine is another term used.

Urhixidur 03:40, 2004 Aug 31 (UTC)

The fact that the Moon seen from the earth appears to be exactly the same size as the Sun has been used by some people to suggest that life on Earth has been set up by some external agent.

Huh? Would you please elaborate?

Slapped wrists - I think this edit was mine, and yeah 'Some people' do include the below ~~freaks~~ searchers for the truth. I can't find any real evidence for it, either. [User:Dave McKee]

Yeah, that's a new one on me. Do "some people" include Billy Joe and his cousin Ralph, UFO cults, or some more distinguished subsection of the population?

Yes, that idea is sheer lunacy. [User:BAD PUN]

Probably so, but someone wrote "This fact has been used by some people to suggest that life on Earth has been set up by some external agent," and if that's true, the article should say so only if it's some appreciable minority of the populace who thinks so--you know, a few wacko exobiologists, or something. --LMS

Hey- Billy Joe here -- <grin> Just because you don't think that the 'coincidence' is important doesn't mean other people don't. In fact, I would expect that if I did a survey in the right environment, that most people would consider the fact that you don't believe it is a sign that an external agent (ie: God) created the earth and all that is in it as a sign that you are close-minded and generally lacking in 'common sense'. That is not to try to be judgemental or derogatory, but the folks that feel this way have as much ability to draw their conclusions from nature as you do.

Billy Joe, if you would please answer my question, I would be happier. --LMS

Hello! I've removed the section on eclipses that referred to coincidences and God. The rest of the section outlines why eclipses occur, and also links to detailed articles about solar and lunar eclipses. --Hellesfarne

But notice that Isil, the Moon in Tolkien's Middle Earth, is male, while Anar, the Sun, is female

I like Tolkien as much as the next person, possibly more, but this does seem kind of out of place here. There are so many mythologies we're not even going to try and represent, why would we single Tolkien's out?

It amazes me that so many allegedly "educated" people have fallen so quickly and so hard for a fraudulent fabrication of such laughable proportions. The very idea that a gigantic ball of rock happens to orbit our planet, showing itself in neat, four-week cycles -- with the same side facing us all the time -- is ludicrous. Furthermore, it is an insult to common sense and a damnable affront to intellectual honesty and integrity. That people actually believe it is evidence that the liberals have wrested the last vestiges of control of our public school system from decent, God-fearing Americans (as if any further evidence was needed! Daddy's Roommate? God Almighty!)

Documentaries such as Enemy of the State have accurately portrayed the elaborate, byzantine network of surveillance satellites that the liberals have sent into space to spy on law-abiding Americans. Equipped with technology developed by Handgun Control, Inc., these satellites have the ability to detect firearms from hundreds of kilometers up. That's right, neighbors .. the next time you're out in the backyard exercising your Second Amendment rights, the liberals will see it! These satellites are sensitive enough to tell the difference between a Colt .45 and a .38 Special! And when they detect you with a firearm, their computers cross-reference the address to figure out your name, and then an enormous database housed at Berkeley is updated with information about you.

Of course, this all works fine during the day, but what about at night? Even the liberals can't control the rotation of the Earth to prevent nightfall from setting in (only Joshua was able to ask for that particular favor!) That's where the "moon" comes in. Powered by nuclear reactors, the "moon" is nothing more than an enormous balloon, emitting trillions of candlepower of gun-revealing light. Piloted by key members of the liberal community, the "moon" is strategically moved across the country, pointing out those who dare to make use of their God-given rights at night!

Yes, I know this probably sounds paranoid and preposterous, but consider this. Despite what the revisionist historians tell you, there is no mention of the "moon" anywhere in literature or historical documents -- anywhere -- before 1950. That is when it was initially launched. When President Josef Kennedy, at the State of the Union address, proclaimed "We choose to go to the moon", he may as well have said "We choose to go to the weather balloon." The subsequent faking of a "moon" landing on national TV was the first step in a long history of the erosion of our constitutional rights by leftists in this country. No longer can we hide from our government when the sun goes down

Oooo... kaaaay. Anyway, assuming for the moment that Earth's moon is in fact real and not an evil government plot of some kind, there's something I'm thinking of doing that I wanted to run past folks in Talk: before starting. It's bugged me for some time that two major articles - one on Earth's moon and the other on moons in general - shared the same page like this. But it's always seemed a little too audacious for me to disambiguate; what would the new pages be called?

A couple of ideas for Earth's moon:

Moon (moon)
Moon (Earth)
Luna

And a couple of ideas for moons in general:

Moon (generic)
Moon (general)
Moon (planetary)
Moon (moon) (yeah, the same as above. It would only be used for one, though :)

Does anyone have any ideas or preferences on this matter? Of course, I would do all of the heavy lifting of changing existing links to point to the appropriate new pages once the article is split. Bryan Derksen, Thursday, May 23, 2002

I think it would be good to try to avoid parenthetical disambiguation whenever possible because you can not easily make direct links to these articles within edit windows.

Becasue there is an obvious ambiguity here, I think the Latin form for Earth's moon (Luna) would be best for that entry and natural satellite would be good for the generic "moon". The word "moon" or "Moon" could then be introduced in the first line of the article and used throughout. Moon would then be a disambiguation page. In general, I think we should try to find valid, and easy to link to alternatives for what we name articles when faced with ambiguity (like what was done with the asteroids articles) and avoid using artificial means for disambiguation (such as the use of parenthesis). --maveric149

Heh. Your timing is impeccable. :) I like your idea of natural satellite, I'll move the article over to that in a little while once some more dust settles. I also agree that parentheticals are nice to avoid when possible (though it's not always possible). Bryan Derksen, Friday, May 24, 2002

(Formerly at Talk:Luna:)

I have had the temerity to apply the "Paris solution" to this article. If there's any disagreement, let's discuss it. - user:Montrealais

I don't much like the the title of this article - hardly anyone refers to the moon as 'Luna'. I would much prefer The Moon, which is the normal english name, and just as unambiguous. Any thoughts? Enchanter

I totally agree. It may be "Luna" to Spanish-speakers, but certainly not to English-speakers. -- Zoe

Depends on how much Heinlein you read. :) However, I'd prefer to just put it at Moon. There are exactly zero links to the moon or the Moon except from this talk page, so I wouldn't call it natural; people just don't tend to include the direct article in the link. A spot check of links to Luna shows a zillion links on the form of the [[Luna|Moon]] (which ain't natural neither). --Brion

It's also "Luna" to Russians, but I think it should be at Moon. -phma

It was strange to me too, why the Luna instead of better or proprier the Moon. In my language we also have two terms (Luna and Mesec). We use Luna more often, but I know Moon is more often used in English. A common error in my language is also writting of Luna in small leter luna, which means general moon of one arbitrary planet. Mesec in lower case means also a month in Slovene, so perhaps that's why we use more often Luna. --XJamRastafire 02:52 Sep 20, 2002 (UTC)

I have moved the Moon back here where it belongs. Note that some of the article's edit history lies at Luna (http://www.wikipedia.org/wiki/Luna&action=history). --Brion 02:45 Sep 20, 2002 (UTC)

Anyone wanna join me in the 21st Century and name this Moon, "Luna" since that appears to be the general global consensus on it's name...this way we can get rid of the disambiguation at the top of the page.

No, then we'd have to put the same disambiguation block on whatever you'd come up with to put at Moon, just like the last time somebody tried that. --Brion 21:07 Nov 1, 2002 (UTC)

Why would somebody mistake Luna for being named Moon or something like that? I mean, geez, that so silly. Lir 21:17 Nov 1, 2002 (UTC)

I heard somewhere a couple of years ago that the Earth has two moons - Luna, and a distant asteroid, which had just been discovered. Perhaps someone would like to add something about it to this article?

You're probably thinking of 3753 Cruithne, which is not a moon of Earth but rather a co-orbital asteroid. I think the proper place to mention it would be in the Earth article, since it has nothing to do with the Moon itself. Bryan

Disappointed to find no Wikipedia article on the Gerstenkorn event. Unfortunately, the only info I have is from 1982 and, I suspect, quite out of line with later thinking. Would be nice to see something, or have I missed it? Cutler 12:21, 24 Feb 2004 (UTC)

Animated Moon phase gif

It's a nice animation, but even with the touchup work I did on it a moment ago the image is still over half a megabyte in size. I think it should be moved out of the main article, both for the benefit of those without broadband and for those who wish to print out the article (the animation would be useless to them). Any ideas on where I should send it? I'm thinking Lunar phase.

Tom Ruen- 5/2/04 - I uploaded the phase animation. Thanks for the impressive touchup! I agree it isn't friendly to have big images on general info pages. Free free to move it if you like. Maybe Lunar phase or maybe better Libration ?

Libration looks good, Lunar phase already has a good image on it. I must say, this animation illustrates libration better than anything I've seen before - I virtually get seasick watching the Moon rocking back and forth. :) Bryan 09:03, 2 May 2004 (UTC)

Far side photo

Would anyone mind terribly if we used a photo of the side of the moon that normally faces the earth? It's great that a photo of the far side is available, but the familiar face would be more appropriate for the beginning of this article. --Yath 19:51, 3 Jul 2004 (UTC)

Why not use them both? I presume you'd want to put the nearside photo in the infobox, so the other one can be moved down into the article text and given a caption there. Bryan 16:08, 11 Jul 2004 (UTC)

It's actually a side photo, half far side, half near side.

Urhixidur 23:36, 2004 Aug 30 (UTC)

Any actions regarding changing the photo? I would also prefer the "normal" view of the near side. Awolf002 16:48, 15 Nov 2004 (UTC)

Why did Urhixidur add "the moon says yes" and "the moon says no"?

Does anyone know why Urhixidur added "the moon says yes" and "the moon says no"?

Bobblewik (talk) 22:03, 30 Aug 2004 (UTC)

Because it moves like a person's head does when (s)he says yes or no. Feel free to clarify. Maybe we should say the "the Moon nods yes" and "the Moon shakes no"...Hmmm, doesn't seem any better.

Urhixidur 23:35, 2004 Aug 30 (UTC)

Ah. I get it. I made an edit that I think makes that clearer (to me anyway). Bobblewik (talk) 23:57, 30 Aug 2004 (UTC)

Caption

Just curious, but was there any reason why the caption under the moon image said "Hold mouse over image for description," and the caption only appeared if I do that? I thought that was silly, so I put the proper caption under the image. - Brian Kendig 19:15, 31 Aug 2004 (UTC)

Where does the moon shine the brighest?

... where the sun doesn't shine, of course!

removed link to landing controversy

I've removed this sentence linking to Apollo moon landing hoax accusations:

For the controversy surrounding this claim, see here. -Wikibob | Talk 23:36, 2004 Nov 22 (UTC)

Inconsistent statistics for lunar orbit

Within the article, there are a couple of problems with the orbital distances in the tables.

Orbital characteristics

Semi-major axis 384,400 km (0.0026 AU)
Orbital circumference 2,413,402 km (0.016 AU)
Eccentricity 0.0554
Perigee 363,104 km (0.0024 AU)
Apogee 405,696 km (0.0027 AU)

Other properties of the Moon's orbit

Mean distance from Earth ~384 403 km
Distance at perigee ~364 397 km
Distance at apogee ~406 731 km

The semi-major axis and mean distance are much the same here, but perigee and apogee differ quite a bit between these two tables. There is no explanation given for these discrepancies.

The figures given for distances in astronomical units (AU) are given to a precision of only two significant figures, even though the distance in kilometres is given to a precision of six figures and the AU is defined elsewhere in Wikipedia with similar precision. If the distance in AU's is to be given, it would be better if these distances were revised to six significant figures to match the precision of the distances in kilometres. --B.d.mills 12:38, 27 Nov 2004 (UTC)

"Selene" and "Cynthion" (sic)

"the terms selene and cynthion refer also to the Moon." Perhaps so. This is just owlish showing-off. These are words used in second-rate Elizabethan poetry and nowhere else. ("Cynthian" not "Cynthion.) This doesn't belong in the opening paragraph. --Wetman 16:46, 15 Dec 2004 (UTC)

The terms are really used, e.g. in http://nssdc.gsfc.nasa.gov/planetary/lunar/loinfo.txt and http://www.hq.nasa.gov/office/pao/History/alsj/a14/a14mr06.htm ; (pericynthion with an o)--Patrick --Patrick 00:38, Dec 16, 2004 (UTC)

Transfer of momentum

I struck out the sentence « (Note however that this slowing is mostly caused by direct tidal friction within the Earths oceans and is not primarily due to the "tidal locking" transfer of momentum to the Moon) » because the distinction is pointless. Earth's rotation slows because it transfers the momentum to the oceanic tidal bulge, which in turn applies torque to the Moon and transfers the momentum to the latter. Angular momentum is preserved, whatever happens. Tidal friction dissipates energy, which is not preserved by this process.

Urhixidur 03:26, 2004 Dec 17 (UTC)

Moon Hoax claims answered by Buzz Aldrin

From the article: "In September 2002, Buzz Aldrin also memorably and very effectively answered the Moon Hoax claims of Bart Sibrel."

I was very interested in reading how Buzz Aldrin dissected those claims, but after a bit of research, I found that the only thing that has happened is that Buzz hit Bart. If this is indeed the case, the present paragraph is somewhat tongue-in-cheek, but only in a way that you can understand if you already know about the incident. Since Wikipedia should probably try to give new info and not read like a geeks humor insider-writeup, I suggest that this sentence be rewritten more clearly.

Moon axes?

Under Origin, it is said that "Tidal forces deformed the once molten Moon into an ellipsoid, with the major axis pointed towards Earth". Can anyone provide a reference that gives the Moon's dimensions (as a triaxial ellipsoid)? I had a devil of a time just finding one (one!) reference for the biaxial dimensions and hence oblateness...

Urhixidur 23:54, 2005 Jan 18 (UTC)

Our table currently lists:

Equatorial diameter 3476.2 km [1] (http://www.onasch.de/astro/showobject.php?lang=en&head=f&anim=129&obj=p03m01)

Polar diameter 3472.0 km

Oblateness 0.0012

The current JPL listing (http://ssd.jpl.nasa.gov/sat_props.html) is (following the 1977 reference to [2] (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WGF-47311PT-9J&_coverDate=06%2F30%2F1977&_alid=273309699&_rdoc=1&_fmt=&_orig=search&_qd=1&_cdi=6821&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=206613e930ef522db6157fb9c68c080f)):

Mean diameter 3475.06 ± 0.06 km (formal standard error)

Also note « an offset of the centre of figure of 1.98±0.06 km toward (19±2)°S, (194±1)°E ».

Apparently, Don Dixon's Universe (Houghton Mifflin, 1981), gives:

Equatorial 3477.8

Average 3476.7

Polar 3475.6

Hence Oblateness 0.00063±0.00003

That's the best we've got so far.

Urhixidur 04:19, 2005 May 3 (UTC)

Addendum: [3] (http://exp.arc.nasa.gov/downloads/celestia/data/solarsys.ssc) gives Moon oblateness as 0.002 and diametre of 3475.06 km (notice the match with the 1977 measurement quoted above).

131.136.242.1 19:14, 6 May 2005 (UTC)

Roman naming?

Why isn't this article named properly? All planets and significant natural satelites have proper roman names. Why would the earth ( Terra ) or the moon ( Luna ) be any different? Just because a thousand people call out natural satelite "the moon" doesn't mean they are right. Give this article it's proper name, Luna.

I disagree with "Luna" being the proper name. This is the "english" dictionary and should reflect the common usage of words. Also, Luna already exists and is a dab page for good reasons. Awolf002 12:37, 16 Feb 2005 (UTC)

Seconded. It should use the name that is most commonly used. And Moon is hands-down the most common. Also, the proper names of natural satellites aren't fixed regardless of language. Moon is the proper name of our natural satellite in English. The page title should reflect that. --Patteroast 13:31, 16 Feb 2005 (UTC)

To the lay person

This article is great. Except - it's too dense with the science. Obviously those writing and contributing are smart and know their stuff but it fails to enlighten the lay reader to basic questions.
For instance: how long is the moons orbit around the earth? "About a month" is the first answer. Scan the article for a more accurate answer and you find a chart with several different "periods" of several different days, with scientific names that don't mean anything to the lay reader. SchmuckyTheCat 16:02, 25 Feb 2005 (UTC)

Is it better now? Here is the second paragraph somewhat expanded:

Several ways to consider a complete orbit are detailed in the table below, but the two most familiar are: the sidereal month being the time it takes to make a complete orbit with respect to the stars, about 27.3 days; and the synodic month being the time it takes to reach the same phase, about 29.5 days. These differ because in the meantime the Earth and Moon have both orbited some distance around the Sun.

-Wikibob | Talk 16:39, 2005 Mar 13 (UTC)

Danger to civilization

The likelihood of it happening "anytime soon" is not a qualifier for it being in the article. If you don't want it in the article, justify why, state your case, not just revert "rv" (I assume you were not calling it "Vandalism"). This is a legitimate topic of discussion, just as the earth could be struck by a meteorite, so could the moon. Stbalbach 21:52, 11 Mar 2005 (UTC)

It is simply not going to happen. Smaller asteroids a few km in diameter or less can threaten life on Earth because of their side effects to the atmosphere or the oceans, but such small asteroids (not to mention mere meteorites) would not break up the Earth or the Moon, they'd just leave a crater. To break up the Moon, an asteroid would have to be several orders of magnitude larger (at least 100 km across, probably more) and there are simply no such large-enough asteroids in Earth-crossing orbits. Those kind of massive collisions occurred in the early days of the solar system, but not now and not in the future... such huge flying debris was cleared away during collisions in the early days of the solar system. All such very large asteroids currently existing are in safe, stable orbits in the asteroid belt.

To summarize, threats to life exist from small asteroids colliding with the Earth, that's well known. But small asteroids colliding with the Moon will just leave a crater, nothing more. -- Curps 22:06, 11 Mar 2005 (UTC)

The article you cite [4] (http://www.exitmundi.nl/moon.htm) correctly points out that the presence of the Moon is important for stabilizing the Earth's axis, and for various reasons the existence of the Moon may have been vital to the evolution of life on Earth. But when they talk about a "super big" asteroid smashing up the Moon, they are doing so in a joking way ("for years we'd have to wear hard hats").

Those kind of massive collisions occurred billions of years ago... one of them probably created the Moon when a Mars-sized planet smashed into the Earth... but all the objects that big are now in stable orbits where they can't smash into each other anymore.

See Copernicus (Lunar crater): it's 800 million years old, and is considered a relatively young crater (see the article)... and that was far, far, far too small an impact to have any chance of breaking up the Moon (you need a telescope to see that crater from Earth, see the lower image on the Copernicus (Lunar crater) page). -- Curps 22:22, 11 Mar 2005

(UTC)

The article cited is part of a larger work about possible earth ending scenarios, the gallows humour of his writing style doesnt mean the subject matter is a "joke". Wikipedia is not original research, we report on what others say. That you personally don't think this could happen doesnt mean it should not be reported. Your certainly free to edit the text to reflect the highly unlikely probabability. The fact is, we dont know all the objects in earths orbit. We dont know what objects might end up in our orbit, say, from the Kuiper Belt. Also who is to say the moon would be "destroyed" it could be knocked off orbit which would knock earths orbit off. Stbalbach 23:06, 11 Mar 2005 (UTC)

Sorry, but I wonder if you're familiar with astronomy. The article you cite makes a serious point about the importance of the Moon for the evolution of life on Earth but merely jokes about us having to "wear hard hats for years" if some "super big" asteroid ever hit the Moon. The article is not seriously suggesting this possibility at all. You are not reporting on what others say, rather you are taking an intentional lighthearted joke seriously.

Please reread what I wrote above about Copernicus crater. The solar system is believed to be about 4.5 billion years old, and the Moon is completely covered with craters. Yet nearly all of those craters are older than 800 million years old... and even those craters are mere craters, caused by objects much, much too small to cause the Moon to break apart or move out of its orbit. The period of intense bombardment ended billions of years ago, and there is simply nothing left in the inner solar system that has both the right orbit and size to break up the Moon.

The Kuiper belt is not a credible source for Moon-smashing asteroids, please cite a reference if you think it is. There are large objects out there, but not only would collisions be very rare, but even if one did occur it would be very, very close to impossible for such a collision to alter the orbit in such a way that it would cross the Earth's orbit (consider the angular momentum that objects have all the way out there, and what it would take to bring them into the inner solar system... remember, we're not talking about mere comets from the Oort cloud, but an object with the size and mass of Sedna or even Pluto).

In a few billion years the Sun will swell up to become a red giant and engulf the Earth and Moon. Based on the last few billion years, we can pretty confidently predict that the odds of the Moon being smashed into fragments by an object during those next few billion years is less than the odds of you or me being struck by lightning in the next five minutes.

-- Curps 23:56, 11 Mar 2005 (UTC)

Thank you for the explanation.

There are people saying the moon is a danger to civilization. It is notable. If you can think of some way of linking the End of Civilization to this article, that needs to be done in some way. What do you suggest? Stbalbach 00:21, 12 Mar 2005 (UTC)

I suggest removing the line about the Moon from End of Civilization. That's an interesting article, with a lot of potential, its credibility shouldn't be marred... there simply is no credible non-facetious scenario involving the Moon blowing up. -- Curps 03:09, 12 Mar 2005 (UTC)

By the way, I followed the link on the End of Civilization page and created an article on Gliese 710. The latest estimate is that its passage may increase the net cratering rate by 5%, which is not much... but at least that's not completely negligible. The moon-blowing-up probability is, I'm afraid (entirely negligible, that is). -- Curps 03:45, 12 Mar 2005 (UTC)

This calls for a new article: Exploding Moon . Thanks for the Gliese article. Stbalbach 06:43, 12 Mar 2005 (UTC)

No, you have not shown us anybody, that says "the moon is a danger to civilization". The article you refer to says, without the moon life would get tougher, and uses a scenario that his highly unlikely to create the effect of removing the moon for illustrative purposes. This is not a notable discussion of the End of Civilization. Awolf002 01:39, 12 Mar 2005 (UTC)

I agree with Awolf, there. I just read the article in question and the "Moon gets destroyed by an impact" scenario appears to be solely intended as an intro to lead into a discussion of "what if the Moon wasn't there?" If the Moon were magically blown up somehow the last thing we'd be worried about would be Earth's axis becoming unstable over geologic timescales; we'd have bigger concerns in the form of kajillions of tons of moonrock falling on us. :) Unless there's some other source for concerns about this "threat", I don't think it's worth mentioning here. Bryan 04:00, 12 Mar 2005 (UTC)

The Exit Mundi (http://www.exitmundi.nl/exitmundi.htm) web site, and article, are explicit about this being a possible End-Of-World scenario. Of course Exit Mundi is not an expert, but, it is a very popular and well known web site, at least in popular culture, it is notable. But just as Exploding whale has not breached the Whale article, my guess is Exploding Moon would likewise be shot down from The Moon. Stbalbach 06:43, 12 Mar 2005 (UTC)

This is intriguing. Obviously, the absence of the Moon is more "unhealthy" to humans than its existence. It would definitely be a mis-classification to call the Moon a "Danger to civilization"! I wonder, if the people at "Exit Mundi" actually think that the piece about the Moon says what Stbalbach thinks it does... As I said, I do not think so. Awolf002 19:53, 12 Mar 2005 (UTC)

I agree that the "Exit Mundi" article is not intended to propose an actual "Moon blows up" scenario, just making the point that "intelligent life wouldn't have evolved without the Moon being there". I don't understand why Stbalbach insists on taking a few clearly facetious remarks at that website seriously. -- Curps 20:12, 12 Mar 2005 (UTC)

The Exit Mundi website is a collection of End of the World Scenarios. Have you looked at it? Stbalbach 03:41, 13 Mar 2005 (UTC)

Yes I have and it's an interesting site, and the authors deal with subjects with an excellent sense of humor. We've argued about this for a while now. The conditions that could result in something smashing the Moon apart existed in the very early days of the solar system. They don't exist now. The South Pole-Aitken basin, mentioned in the exitmundi.nl article, is believed to be 3.9 billion years old [5] (http://www.lpi.usra.edu/meetings/moon99/pdf/8017.pdf); it is literally the oldest observed feature on the Moon. There was a lot of extremely large debris flying around in those early days, but it's just not there anymore, as a result of multiple collisions and objects ejected out of the solar system in those very early days. By contrast, in the last 0.8 billion years there have been no more than a handful of impacts on the Moon that would even create a moderate-sized crater like Copernicus (less than 100 km in diameter). -- Curps 04:17, 13 Mar 2005 (UTC)

We seem to be talking at cross purposes. I am not disputing your position. It would be better said in an article than a talk page. Stbalbach 00:23, 14 Mar 2005 (UTC)

Verifying data

User:B.d.mills pointed out discrepancies between the infobox and other table so I tried to check some against references. Before the long checklist below, does anyone know what references were used for the data in the infobox and tables? I would like to add reference footnotes to the infobox at some time.

JPL's HORIZONS System (http://ssd.jpl.nasa.gov/cgi-bin/eph) gives:

Revised: Mar 11, 1998             Moon / (Earth)                            301

PHYSICAL PROPERTIES:
Radius, km            = 1737.53+-0.03   Mass, 10^20 kg        =  734.9
Density, gm cm^-3     =    3.3437       Geometric albedo      =    0.12
V(1,0)                =   +0.21         GM, km^3/s^2          = 4902.798+-.005
Earth/Moon mass ratio = 81.300587       Surface gravity       =    1.62 m s^-2
Nearside crust. thick.= 58+-8 km        Farside crust. thick. = ~80 - 90 km
Heat flow, Apollo 15  = 3.1+-.6 mW/m^2  Heat flow, Apollo 17  = 2.2+-.5 mW/m^2
Mean crustal density  = 2.97+-.07g/cm^3 k2                    = 0.0302+-.0012 
Induced magnetic mom. = 4.23x10^22Gcm^3 Magnetometer moment   = 435+-15

DYNAMICAL CHARACTERISTICS:
Mean angular diameter = 31'05.2"        Orbit period          = 27.321582 d
Obliquity to orbit    = 6.67 deg        Eccentricity          = 0.05490
Semi-major axis, a    = 384400 km       Inclination           = 5.145 deg
Mean motion, rad/s    = 2.6616995x10^-6 Nodal period          = 6798.38 d
Apsidal period        = 3231.50 d       Mom. of inertia C/MR^2= 0.3935+-.0011
beta (C-A/B), x10^-4  = 6.31(72+-15)    gamma (B-A/C), x10^-4 = 2.278(8+-2)

infobox comparision

JPL's Radius gives a diameter of 3475 km but no oblateness, while the article gives an equatorial diameter of 3476.2, and a polar diameter of 3472.0, and an oblateness of (3476.2 - 3472.0) / 3476.2 = 0.0012. Close enough I'd guess.

JPL's Density rounds nicely to the infobox figure of 3.344 g/cm3.

Infobox Gravity of 1.622 is more accurate than JPL.

JPL's mass of 7.349x10^22 is different from the article's Infobox Mass of 7.347673x10^22, which however is consistent with a lunar mass calculated from (Earth's mass) 5.9736×10^24 / 81.300587 of 7.3475x10^22, within the error limits.

Orbital period (sidereal I assume) matches to 5 figures.

Semi-major axis matches.

Eccentricity (mean assumed) however is somewhat different with the infobox's 0.0554 compared to JPL's 0.0549. Could this be due to different definitions of mean, or the mean is taken over different time period? It seems the Moon's perigee varies by +/- 2% over the year, with the apogee varying by only around +/- 0.5 % (see http://www.fourmilab.ch/earthview/pacalc.html), so maybe the eccentricity is that of an idealised orbit (a perfect ellipse?) before the Sun's influence is applied (I'm not an expert here).

I see the German de:Mond gives perigee as 356410 km, which looks suspiciously like the nearest the Moon gets to the Earth at any time, and not a typicial perigee, nor a layman's average perigee. Maybe this should be explained?

other table comparision

Eccentricity of 0.0549 matches JPL's (and the German article) but differs from the infobox.

Mean perigee of ~364397 km and mean apogee of ~406731 km are different from the infobox and are not consistent with the table's eccentricity. Using d_a=apogee, d_p=perigee from :<math>e={{d_a-d_p}\over{d_a+d_p}}<math> where <math>d_p\,\!<math> is perigee and <math>d_a\,\!<math> is apogee, e is (406731 - 364397) / (406731 + 364397) = 0.05489879 (contrast 0.0549003), while the infobox figures give e = (405696 - 363104) / (405696 + 363104)=0.0554006243 (consistent with 0.0554). Rounding errors for the table data don't seem to explain the contrast.

Table's Mean inclination of orbit to ecliptic orbital of 5 degrees 9 minutes appears rounded from the infobox's 5.145396° (5 degrees 8.72376 minutes) which is consistent with JPL's 5.145.

I didn't check anything else, and I may well have made errors myself! -Wikibob | Talk 20:41, 2005 Mar 13 (UTC)

buying land on the moon?

I've been bought a plot of land on the moon as a birthday present. A certain Mr Dennis M Hope claims to own the moon, and his pal Francis P Williams (Lunar Ambassador to the united Kingdom)from MoonEstates.com claim to be the only authorised reseller of lunar land. They also claim they own the other planets too. Is this worth the paper its written on? Can someone really own an astronomical object just because the law on earth about ownership pretty much allows anything? Has my friend been conned?Soloist 14:07, 24 Mar 2005 (UTC)

See Outer Space Treaty. — Monedula 14:20, 24 Mar 2005 (UTC)

Hopefully not terribly much so. These guys end up on the news every now and again for the laugh effect. For now, the moon and other celestial bodies remain under the common property of all mankind, like the oceans. In historical practice land ownership has come from incumbency of some kind on the land in question. If you're ready to stake your claim and put up a homestead on the moon, then by all means, go for it. Otherwise, enjoy the worthless piece of paper. --Alexwcovington (talk) 17:16, 24 Mar 2005 (UTC)

Online moon maps and photo resources

Are there any other online moon map and photo resources that support direct links with URLs indicating latitude and longitude? If there is, then I thought it would be cool to extend the concept of Wikipedia:WikiProject_Geographical_coordinates to also including the moon, and perhaps also planets and starmaps. For your enjoyment, I have made some experiments on Amundsen (crater) and Aristoteles (crater) sattelite craters. The map sources currently know about the Clementine images, the LPI moon atlas plus NASA World Wind with the moon add-on. -- Egil 10:42, 25 Mar 2005 (UTC)

The reaction was one of skepticism. Ive been told there is little value in the online images, and that the perspective one might reach by navigation of this kind on the moon is probably without value (I personally found travelling, starting from one of the craters, exploring the neighborhood using NASA World Wind moon overlay quite fascinating. But then I am only a total novice on this subject.) I have thus reverted the changes to navigatable coordinates, and left them as pure unstructured text. If someone wants to pursue at a later date, that is of course possible. Just use the ideas from Wikipedia:WikiProject_Geographical_coordinates, adding the attribute globe:Moon. -- Egil 08:02, 26 Mar 2005 (UTC)

No, my reaction at least was that it was a very interesting idea that worked very poorly in practice, because of the marginal quality of the available online image sources. As I mentioned on your talk page, lookup by latitude/longitude (as opposed to lookup by feature name) works very poorly with the Orbiter images website (a limitation or bug of that site's lookup feature), and the online Clementine images website also leave a lot to be desired (mediocre resolution and detail, no labels, not really useful except for the largest craters). As for World Wind, I haven't tried it but it requires installing special software on each user's PC, requires a high-speed Internet connection, really needs a 3D accelerator graphics card (ie, user's PC must be less than two years old), so it won't be available to most users. If someone ever implements an online map of the Moon that works something like Mapquest.com, this idea could definitely be revived. -- Curps 13:28, 26 Mar 2005 (UTC)

The moon images of World Wind are in fact part of the installation, so an Internet connection is not required for the Moon layer. Except for initial downloading of the layer, of course (the hi-res is 40 megabytes of compressed data, the low-res 3-something). That said, I've been told an Internet connection is required to enjoy Wikipedia properly, also. -- Egil 15:53, 26 Mar 2005 (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)

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 nebula NGC 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.

Urhixidur 17:47, 2005 Apr 25 (UTC)

Lunar orbital precession

Is the Sun or the Earth's equatorial bulge mainly responsible? This source (http://www.nap.edu/openbook/030907438X/html/400.html) states the Sun dominates, but the article is about the precession of the perigee, not the precession of the nodes. This later page (http://www.nap.edu/openbook/030907438X/html/403.html) 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.

Urhixidur 17:28, 2005 Apr 25 (UTC)

One or two or more moons?

The change in the introduction should be improved. Although there is an asteroid "in orbit" [6] (http://www.space.com/scienceastronomy/solarsystem/second_moon_991029.html), 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. Awolf002 17:20, 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. --Patteroast 07:30, 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)

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