Talk:Full moon

Folklore
However, Dr Timo Partonen of the Finnish National Public Health Institute carried out a study of 1400 suicides and found that people were more likely to make an attempt on their life when there was a new moon. Unless people disagree, I'm going to remove this text as it refers to a new mooìn rather than a full moon. lxowle (talk) 03:59, 20 July 2010 (UTC)
 * I dont objectTwonumbers (talk) 13:00, 22 June 2011 (UTC)

Suggested Edit
Its absolute maximum size occurs at the moment expansion has stopped, and when graphed, its tangent slope is zero. I suggest removing this line all together - it is a complex way of saying something simple. lxowle (talk) 03:55, 20 July 2010 (UTC)

Capitalisation
Does Full Moon always have to be capitalised? --Guinnog 23:29, 27 October 2006 (UTC)
 * I'm not sure what the spelling rules are, but most likely they differ per country. IMNSHO people shouldn't follow such micro-management by spelling committees anyway.  Personally, I prefer writing names of celestial bodies with capitals. Tom Peters 09:22, 28 October 2006 (UTC)
 * I don't have a problem with that, but it should be consistent with the article title. If it is to be spelled with capitals, the article should be moved to Full Moon. A similar argument applies to New moon -> New Moon. --Guinnog 10:35, 28 October 2006 (UTC)


 * Full Moon is currently a disambig page, New Moon is a redirect to New moon... --Guinnog 10:43, 28 October 2006 (UTC)

Manual of Style (capital letters) has "The words sun, earth, and moon are proper nouns when the sentence uses them in an astronomical context..." --Guinnog 10:50, 28 October 2006 (UTC)


 * It should not be capitalized. Since moon in this sense refers to the phenomenon seen from Earth, the lowercase usage is appropriate. I do not recall ever seeing the usage "full Moon" in print. (See, for example, Merriam-Webster’s entry.) — Knowledge Seeker দ 17:57, 28 October 2006 (UTC)
 * correct Twonumbers (talk) 00:22, 26 June 2011 (UTC)


 * I disagree on the capitalization you suggest. The use of "moon" can refer to any satellite of a planet, while "Moon" is the Earth's moon... -- Jokes Free4Me (talk)

Is this true?
I got this in some random e-mail with a bunch of 'facts'.

February 1865 is the only month in recorded history not to have a full moon. Not true. Since a lunar month has an average duration of about 29.5 days and February usually has only 28 days, there are occasions when there is no Full Moon in February. Last occurrence was in 1999, next one in 2018. See: http://aa.usno.navy.mil/data/docs/MoonPhase.html Tom Peters 07:19, 25 July 2006 (UTC)
 * There's also the fact that there was a full moon on Feb 10, 1865 Saros136 (talk) 01:30, 8 February 2008 (UTC)

Merging material into Blue moon
The material at Full moon should probably be merged into the Full moon article. Blank Verse  &empty;  16:25, 11 Apr 2005 (UTC)
 * I assume that you mean that it should be merged into Blue moon. This has been done. --Theo (Talk) 14:23, 10 May 2005 (UTC)

That's amore
I deleted the statement: The moon is also the inspiration behind a song containing the lyrics: "When the moon hits your eye, like a big pizza pie. That's amore". I think it is too general for this article. I will see if it makes a useful addition to Moon. --Theo (Talk) 14:23, 10 May 2005 (UTC)

Cheese
In a similar vein, I am removing the statement that cartoons usually depict the moon as being made of cheese. There might be a place for that, but it doesn't belong on a scientific page on full moons. Kafziel 19:04, 21 July 2005 (UTC)

Harder!
My mom says that it is harder to sleep when it is full moon, is this true?
 * Maybe for you, because the gravity is affected on a full moon. 23:09, 13 September 2011 (UTC)
 * I have trouble sleeping during a full moon until i adjust the curtains. Otherwise I get the moon shining right in my eyes. Zyxwv99 (talk) 15:19, 10 December 2012 (UTC)

Cops
Whatever the headshrinkers may theorise, ask any cop what effect the full moon has. Noone wants to be working nights around a full moon.
 * Exactly. You cannot do statistics on the memory of any one cop of his experiences.  If instead you take a decent big sample of verifyable observations, then you will find that that there is NO relation between the phase of the Moon and almost everything else.  Two reasons why people believe otherwise:


 * 1) a Full Moon is more conspicuous than any other phase, so people are more likely to notice the phase of the Moon;
 * 2) a Full Moon is visible the whole night (in contrast to partial phases), and the Moon appears full for about 3 or 4 nights on a row.  So there appears to be a Full Moon in the sky for much longer than 1 night, so statistically events will be reported more often as taking place during a Full Moon than would be predicted from an astronomical calculation.
 * You also didn't mention that you don't need a flashlight when breaking into a house on a full moon, it's an easier time to commit a crime. I understand what you mean by many people precieving the full moon lasting alot longer than it actually is, but any one who's worked in a fraternity ward knows the difference between a night with a full moon, and without.

Added (Cats to Clean)
Best regards. Delete template at will so long as point three handled. // Fra nkB 20:17, 18 December 2006 (UTC)
 * 1) Section is too terse, transform more like New Moon. This won't do.
 * 2) There is no reason to make users follow a link to get a full explaination as we have no deadtree page limits. IMHO, the math should also be explained here.
 * 3) The reference to a text was supposed to be in a ref block perhaps? That should not be explicit either, when has any other encyclopedia referred to a specific equation in a text book?

Duration
How long does a full moon (or any other phase of the moon, for that matter) last? 81.156.250.78 02:19, 19 February 2007 (UTC)


 * 1.0 moments. Before this moment it is called waxing gibbous, and after is called waning gibbous. See Lunar phase. Mikeeg555 (talk) 03:49, 6 March 2009 (UTC)

Is the definition wrong, or not precise enough?
At the moment, the definition (first paragraph of the the article) uses this dual condition: "when the Moon is on the opposite side of the Earth from the Sun, and when the three celestial bodies are aligned as close as possible to a straight line".

This is inconsistent: if the Moon is truly on the opposite side, the three bodies would, in fact, be in a straight line. It is also overly vague: "as close as possible" without what? In other words, what would we have if the three bodies were truly in a straight line? The answer to this question, I believe, is the key to a more proper definition: a Full Moon occurs when the Moon is furthest from the sun in a given lunar cycle, and the three celestial bodies are at their closest to being in a straight line without being exactly in a straight line. My second condition is needed because, when the Moon is furthest from the Sun in a given lunar cycle and the bodies are exactly in a straight line, the Earth's shadow completely covers the Moon, and we have a full lunar eclipse rather than a Full Moon.

Actually, the Earth's shadow can completely cover the Moon even if the bodies are not exactly lined up. Additionally, there are intermediate situations, which are different types of partial lunar eclipses. See: http://en.wikipedia.org/wiki/Lunar_eclipse, http://starryskies.com/The_sky/events/lunar-2003/eclipse1.html , and http://starryskies.com/The_sky/events/lunar-2003/eclipse2.html.

I'm not an astronomer, but I know a bit of solid geometry, and I know a vague phrase when I see it!

SeanStreiff 19:43, 5 June 2007 (UTC)
 * Actually it is imprecise. The time of the closest angular approach of the Sun and Earth, as seen from the center of the Moon, is not exactly the same as the opposition. This is because at the time the Mooncentric latitudes of the Earth and Sun are changing, either getting closer or farther apart. The Full moon opposition is very close in time to the minimum distance, though. Saros136 (talk) 06:16, 7 February 2008 (UTC)
 * I came here to make the same point. In fact, last week on QI, Stephen Fry stated that the state of affairs when the sun, moon, and earth are in a straight line, with the earth in the middle, is a full moon - when it would actually be a lunar eclipse. One could argue that a lunar eclipse is a special case of a full moon... David 11:47, 25 October 2007 (UTC)


 * I fully agree, the way it's worded is very misleading - a straight line, or even near to it, results in a lunar eclipse, not a full moon. It's a shame that nobody bothered to fix this, because now it's on the main page with the very same mistake. 67.163.165.236 (talk) 08:32, 12 January 2008 (UTC)
 * A full moon and a lunar eclipse are not mutually exclusive events. And neither is a lunar eclipse a special case of a full moon. A full moon is the instant when the goecentric ecliptic longitudes of the Moon and Sun differ by 180 degrees. Sometimes the Moon is eclipsed at the time, sometimes not. Saros136 (talk) 05:48, 7 February 2008 (UTC)
 * I just checked things out with SOLEX 9.1 At the next full moon, there is about a five minute difference between the least angular difference and the opposition (full moon). The latter agrees with the full moon time from the NASA eclipse page Saros136 (talk) 07:14, 7 February 2008 (UTC)

I looked in an almanac and it seems full moon and opposition do not occur exactly at the same time (about one hour). I'm looking for more info. 22 January 2008.
 * Must be some mistake. They are the same thing. Saros136 (talk) 05:48, 7 February 2008 (UTC)

wrong definition of full moon
According to the definition in the article, full moon is when the Earth, Sun, and Moon are as close to a straight line as possible. From the Earth, this is when the angular distance between the Sun and Moon was the greatest. Using ephemeris from SOLEX 9.1, I found the max difference (near the next full moon) came at 3:27:46 TDT, and opposition at 3:31:36 TDT. (Out of curiosity, I compared the opposition time to the algorithm from Astronomical Algorithms, by Meeus. Meeus' time for the full moon was two seconds later.) A 3:50 difference. (The answer was slightly different when I used the smallest Sun-Earth difference from the Moon). Gotta correct the definition. Meeus gives the apparent geocentric longitude definition. Saros136 (talk) 07:59, 7 February 2008 (UTC)
 * When the earth, sun, and moon are aligned, how does the earth NOT block the light getting to the moon? How is there EVER a full moon? Surely for the moon to be in the night sky, it's in our shadow automatically. —Preceding unsigned comment added by 75.72.21.221 (talk) 03:23, 21 February 2008 (UTC)
 * Hi. I mentioned a possible difference between the times of full moon and opposition. It was an error on the website I consulted, which used a redundant, less accurate algorithm for opposition. I'm sorry for reacting too fast. Although astronomy can get complicated, I think there is no ambiguity that they are strictly the same, as per Meeus' definition. Jblndl (talk) 19:43, 22 February 2008 (UTC)

eclipse
Perhaps add something to address this question. Because of the inclination of the moon's orbital plane on the ecliptic plane (5°), the moon is usually not in the Earth's shadow at that time (angular size 1°23'). When the moon's orbit is close enough to the ecliptic at the time of opposition, and the moon enters partially or totally the Earth's shadow, the event is a Lunar eclipse. Jblndl (talk) 14:31, 22 February 2008 (UTC)

Native American Names
I would like to see some citation for these names. And some citations that are based on the specific languages and cultures of Native America, not some New Agey book that lumps all these cultures together. To me, these names look like some archaizing projection. There was not just one "Native American language" and it's very unlikely that all of them, even in the "northern and eastern United States" used similar terms. It's true that the planetary associations with the days of the week are very similar from Ireland through Korea, but this is probably due to the influence of Babylonian astronomy. In India, despite the importance of Sanskrit astronomy, the names of months and the dating of new year days varies greatly across the sub-continent. I imagine the same is true for "Native American" names for the months. Inter lingua 16:44, 8 September 2008 (UTC)
 * Agreed on lumping all Native Americans together. The source says, "There was some variation in the Moon names, but in general, the same ones were current throughout the Algonquin tribes from New England to Lake Superior." . Article edited. Note on spelling: the passage obviously refers to Algonquians in general and not the specific Algonquin tribe. 198.189.164.204 (talk) 02:19, 3 March 2010 (UTC)
 * The actual Algonquin names are different. The source of this is originally The Farmer's Almanac, which is not exactly a scholarly source.

the moon's apparent brightness
The illuminated area of the moon, as seen from the earth, rises and falls through the moon's various phases, as we know. Its apparent brightness, based on the light from the sun to the moon, reflected or scattered back to the earth, also rises and falls accordingly. As the moon nears Full moon, it's apparent illuminated area increases slowly to a maximum and then decreases slowly away from that, similar to the peak of a sine wave. A second effect is that humans are not especially sensitive to changes in brightness; our perception to brightness changes is often spoken as being logarithmic. So we should expect our perception to be that the moon would appear to be close to it's brightest for several days leading up to the Full moon and for several days thereafter. However, instead it appears to be MUCH brighter right at the Full moon, and perhaps for one day before and after.

I'm wondering if the reflectivity of the moon to the earth isn't much higher right when the light angle from the sun to the earth is very close to 180 degrees, and we're not relying so much on light-scattering and off-angle (non-180-degree) reflectance to get our moonlight. Perhaps the Full moon really is MUCH brighter? Perhaps someone knows where to look up measurements of this effect, assuming that it's real. 98.216.52.158 (talk) 09:56, 15 October 2008 (UTC)

"appears round" (but is not actually?)
Am I right in thinking that it only appears round, but is in fact, not a circle, but an ellipse? --Rebroad (talk) 22:59, 20 October 2008 (UTC)
 * It's approximately round. The craters, mountains, valleys, etc., modify this. Additionally, when the moon is close to the horizon, refraction from the atmosphere makes it appear flattened -- wider than tall. Victor Engel (talk) 14:41, 14 September 2011 (UTC)

Query on moon's position
I am no astronomer but it seems to me that the one time you cannot have a full moon (see opening para of the article) is when the moon is on the opposite side of the earth from the sun. Surely this is when there will be maximum earth shadow across the moon as the earth will be directly between the sun and the moon?? Am I being thick here?

Further. . . if the stated positioning was in a completely straight line, then it seems to me that there would be a total eclipse of the moon, which is about as far as you can get from a full moon. I'm sure I must be missing soemthing here but I would be very grateful if someone can tell me what. Gurumaister (talk) 19:30, 21 December 2008 (UTC)


 * Well, the shaded area of the moon is normally the moon's own shadow from the sun, not the Earth's shadow. Thus on Earth we see the moon get the most sun when the sun and moon are opposite, giving us a full moon. On the occasions where the Earths shadow does touch the moon, we get a lunar eclipse. Ikmxx (talk) 05:47, 28 October 2012 (UTC)

Main image
I propose that the main image becomes:

It's a simplified version of the full moon (so no picture) to bring article in line with other moon phase articles … KVDP (talk) 12:19, 6 October 2009 (UTC)
 * Good point Twonumbers (talk) 10:12, 29 June 2011 (UTC)

Name and date of spring moon?
The moon names section contains the following: "the Egg Moon (the full moon before Easter) would be the first moon after March 21".

But according to the Easter section of Claus Tøndering's Calendar FAQ, Easter is "the first Sunday after the first Full moon on or after the Vernal Equinox [emphasis mine] (the FAQ then explains that the "official" Vernal Equinox, on 21 March, is usually used for this calculation, rather than the actual Vernal Equinox, which may differ from the official one by a day or two). So which is correct?

The FAQ also says that this full moon, because it's associated with Easter, is called the Paschal Moon. Perhaps this name should be added to the "alternate names" section? — 188.28.84.150 (talk) 08:01, 16 September 2011 (UTC)

Sock disruption?
Protection due to ongoing sock disruption? Anyone mind translating this into English, please? Victor Engel (talk) 20:24, 7 October 2011 (UTC)

Myths
Some myths are based on the full moon, like the werewolf. Also, on H2o (a popular mermaid show) there is a part about the full moon. It's always the full moon, why are some myths based on only the full moon? Why not a half moon or anything else? Any answer would help! ~ Angielmawesomeness — Preceding unsigned comment added by Angielmawesomeness (talk • contribs) 04:10, 10 December 2011 (UTC)

Is the idea of a definitive list of English names misleading?
Currently November is showing as "beaver" moon which sounds suspiciously like it might be N. American.

Generally worried about potential conflation of sources which has resulted in an "English name" and "Other names" division.

The following site has separate categories for "colonial american" and "medieval english" http://home.hiwaay.net/~krcool/Astro/moon/moonnames.htm

Futhermore there is a reference to "Egg Moon" under "Full moon names" which does not appear in the table immediately below

Scanning other sites shows variation even within attributions to English/Colonial categories http://tbtf.com/archive/1999-01-04.html#s09 http://www.fullmoon.info/en/blog/fullmoon-names.html This one tries to give sense to different timings for Julian and Gregorian as well as cultural changes http://www.celticmythmoon.com/moon.html

So, in short - the current tabular presentation seems to be misleading if not inaccurate. I am unsure how definitive we can be given the amount of variation which is being recorded in the secondary sources I have seen. However, just moving information from English to expand the "Other" column would be unsatisfactory in terms of legibilty.

Maybe a separate table for English traditions? This loses the ability to scan across a Gregorian month to see all equivalents, but, given the complexity of the English data compared to the others, may be the answer Mcgladdery (talk) 08:44, 3 September 2012 (UTC)
 * I agree that the table format isn't working out.
 * The Algonquian names are sourced to http://www.wwu.edu/depts/skywise/indianmoons.html which links at the bottom to its source of http://americanindian.net/moons.html (scroll down for gigantic list). There's no obvious reason to list just this one culture's moon names, out of all those available.
 * Even more unfortunately, that's the only sourced column in the entire table.
 * Unless quite a bit of work is put into the table, it might be best to just remove the entire thing, and replace it with a paragraph pointing out the huge variety of regional names for each moon, with a handful of examples and links to RSs. Not sure. -- Quiddity (talk) 19:07, 3 September 2012 (UTC)
 * I think we should scrap all the moon names, as the sources are, for the most part, not reliable (personal webpages, mostly), and don't actually give much provenance for the information, although one of the new links on the Wolf Moon page goes to a dateable/traceable document, namely, The New England historical & genealogical register vol 10 (1856), which shows a source of some of the names which was written back in 1650. I think the section is poorly referenced, displays some bias, and hopelessly tendentious.--Vidkun (talk) 13:10, 5 September 2012 (UTC)
 * The current batch, yes; but there must be some RSs out there, it just needs some work to find and use them.
 * eg (hmm, they seem to re-use the same list every year, again concentrating on Algonquian names, which is weird (possibly circular?))  (ditto),  (I'd guess the Falmer's Almanac is the original source of this Algonquian abundance?).
 * For wiccan/witches' names, this might be suitable, written by Ann Moura.
 * For Sinhala, Poya seems to cover this, and contains some links (some broken). This or this might work as a ref.
 * etc. (That's about all the interest I can scrape together. The rest is up to someone else!) HTH. -- Quiddity (talk) 20:46, 5 September 2012 (UTC)

the "table of full moon names" has been an eyesore for years, but nobody seems to be willing to fix it. I mean come on, what does it contain?
 * "Farmers' Almanac names (referenced to ) Algonquian names, referenced to some website, "other names" (unreferenced), Hindu names (unreferenced), Sinhala names (unreferenced).

Even if it wasn't for the referencing problem, what sort of selection is this? "Farmers' Almanac, Algonquin, other, Hindu, Sinhala"? I am now removing this thing, convinced that the action results in a better article. --dab (𒁳) 13:00, 3 May 2013 (UTC)

Pink Moon in April?
--Robert Saunders (talk) 21:10, 3 September 2012 (UTC) Should "Pink Moon" not be added to the list of names for the April full moon? I'm no expert but there are various references online, including this one on the National Geographic website: http://science.nationalgeographic.com/science/space/solar-system/full-moon-article/

Northern Native Americans call April's full moon the pink moon after a species of early blooming wildflower. I am sorry, but I am tired of these made-up or unverifiable names based on "Native Americans". These "Native Americans" have names, and languages, and they used to fill an entire continent. So if anyone wants to claim "Native American" derivation of such a name, let them specifiy which people, which language, ideally first attestation, and a reference to a dictionary or something. Otherwise I am afraid it must be treated as "Farmers' Almanac" cruft, and whoever brings up the name must be considered a primary source.

It almost seems Farmers' Almanac is proud of their role in generating fakelore. Of their "traditional" moon names, the only ones that seem to based in actual folklore are "harvest moon" and "hunters' moon". These are also known to OED, and can be traced to 18th century England. All ther other, US-specific name need a decent reference to their origin and earliest attestation.

"Pink moon" seems to be the latest to join this illustrious group. I find it attested for 2009, but it only seems to have been picked up by journalists this year. It's difficult to research, because Pink Moon is a 1972 record. It turns out that FA used "pink moon" before 2009, based on these pages,. --dab (𒁳) 13:23, 3 May 2013 (UTC)

History of "Farmers' Almanac" "lunisolar" system
The earliest "Farmers' Almanacs" began to be published in the late 18th century, i.e. they did not so much report as contribute to the formation of American folklore. I just found that they seem to have a predecessor in The Boston ephemeris,  an almanack published in the 1680s. But the "Boston ephemeris" isn't particularly interested in the moons, it just gives the phases and does not record any fanciful names. This therefore becomes a topic of 18th-century history, it would be interesting to trace the development of American almanacs connecting the 1680s and the 1790s and see if the full moon names pop up at some point. --dab (𒁳) 13:45, 5 May 2013 (UTC)
 * an online search seems to suggest they did not. The "Farmers' Almanacs" may be old, but the fashion of naming full moons seems to originate in the 1930s only. So perhaps this isn't a "Farmers' Almanac" innovation and they merely adopted it c. 1940? In this 1933 source, we get an answer to the question "what are the names of the Indian months" in Dan Beard's Scouting Section. The answer is unambiguous,
 * Moon of Difficulty, Racoon Moon, Sore Eye Moon, Goose Egg Moon, Planting Moon; Strawberry Moon, Buffalo, Harvest, Wild Rice, Nuts, Deer, Wolves, see p. 78 "Signs, Signals and Symbols" by J. B. Lippincott Co., Philadelphia Pa.
 * we see that some of the "FA" names are already present here, especially "Racoon Moon", "Strawberry Moon" and "Wolves". This now seems to become part of romanticized "Indians" fiction of the 1930s boy scout subculture.  --dab (𒁳) 13:54, 5 May 2013 (UTC)

It turns out that Dan Beard is citing his own work, American boys' book of signs, signals and symbols published 1918. On p. 78, there is The Buckskin Calendar including a list of "Indian moons", as above,
 * Difficulty, Racoon, Sore-Eye, Goose-Egg, Planting, Strawberry, Buffalo, Harvest, Wild Rice, Nuts, Deer, Wolves

This is at present the earlist known list of "pseudo-Indian month names". Beard has apparently just made them up, he isn't claiming these are actual Indian names, they are just intended for the purpose of "second class scouts" who apparently pretend-played at being Indians, intermediate between the Tenderfeet rank, which just uses the Julian names, and the Pioneer rank. So my theory is that Beard (1918) came up with "Indian month names" for the boy scouts, and that these name somehow entered popular usage, and came to be picked up by the Farmers' Almanacs by the 1930s or 1940s. People then tried to find the "real" Indian names of these months, introducing new names or trying to find explanations for them. --dab (𒁳) 14:02, 5 May 2013 (UTC)

This is surprisingly difficult to research. I have now compiled what I could find about the history of these almanacs at American almanacs. Looking through 19th-century examples of such almanacs shows no traces of "Indian moon names", but I admit I could not find any 19th century copy of the Maine Farmers' Almanac. So far we know that "Indian moon names" were a thing among the American boy scouts from at least 1918, and that Maine Farmers' Almanac printed such names (but which ones) from at least the 1930s. That's a terminus ante quem, but no more, but I do have the impression that this is a development of the early 20th century (when "Native Americans" came to be seen as romantic, viz. after the end of the Indian wars of the 1870s at least). Thanks to Sky & Telescope we have some information about the term blue moon,
 * With help from Margaret Vaverek (Southwest Texas State University) and several other librarians, we obtained more than 40 editions of the Maine Farmers' Almanac from the period 1819 to 1962. These refer to more than a dozen Blue Moons

but unfortunately this, taken at face value, only says "more than a dozen in the period 1819-1962", it doesn't say if any of this dozen are from the earlier part of this span. Theoretically, you get 14 blue moons in 38 years, so the "more than a dozen" could easily fit into the 20th century. Plus, of course, "blue moon" is not one of the "Indian" group of names, and may occur before, or independent of, the "Indian" thing, it's just an indication that this publication began to care about the moon more than others, as most almanacs just give you the moon phases and nothing more.

It seems that the tradition of listing moon names by Native American tribe began in popular "moon mysteries" books of the 1990s. The supposed native names are still unsourced and highly questionable, but they must have some source (these authors all copy from one another, and it will eventually turn out somebody made this all up, but it will be interesting to see who and when). It seems there is a genuine "colonial" New England tradition which claims moon names based on Algonquin, even if this isn't necessarily true the existence of the tradition itself is factual, and presumably goes back to the 19th century. --dab (𒁳) 09:36, 6 May 2013 (UTC)

Minor grammar changes
The first two sentences of the article both appear to be missing the word "is". In the first sentence, "when the Moon completely illuminated" should be "when the Moon is completely illuminated". In the second sentence, "the Moon in opposition" should be "the Moon is in opposition".Wcomm (talk) 05:50, 10 May 2013 (UTC)

Moonrise
Does the moon really rise up to 50 minutes later each night? I find this hard to believe. Bear in mind that sunrise is approximately 2 minutes later per day in summer time (and 2 minutes earlier in winter.)

Sincerely, Mike — Preceding unsigned comment added by 82.24.113.163 (talk) 23:39, 23 June 2013 (UTC)


 * The 50 minutes a night is an average, the tilt of the earth and the fact that the moon's orbit is elliptical instead of circular make the exact amount a bit complicated to calculate. Figuring the seconds must be a pain =) The time of moonrise isn't affected by the time of sunrise at all though. Ikmxx (talk) 18:57, 3 August 2013 (UTC)

The calculation, if done [Steve in-]correctly, gives an average of 54.7078 minutes. All the references I have found on the net either use the wrong lunar orbit period of 29.5 instead of the siderial period. 27.32166 and/or assume, implicitly in their calculation method, that the moon stops after 24 hours to let the earth catch up. This is implicit in the concept that the earth has to turn one day's worth more of moon revolution to catch up and ignores the fact that the moon still moves as Earth is doing its catch up after the 24 hour mark. I found two college astronomy pages with these errors! The time is NOT 24/29.5 as shown in a earlier paragraph and those who show that either simply copied it from somewhere else with it wrong, or don't understand uniform motion. It is a more complex, though not very difficult calculation that can either be based on calculating the catch-up time using the difference of the speeds (like hands on an analog clock), or solving the simultaneous equations of the two bodies using D=RT (Distance=Rate x Time). Even the NASA site has the 50 minute time. I'm waiting for responses from several other sites hoping to find someone with the skills to reason it out correctly. Regards, Steve &#32;-- Steve --  (talk) 08:53, 27 November 2013 (UTC)


 * I reverted the changes. 24/29.53 hours (48.76 min) is correct, or closer than your answer. In the sun-earth rotating reference frame, the earth turns once per day, and the moon orbits in the same direction once every 29.53 days. I come up with 1/28.53 days = 1440/28.53 minutes = 50.47 minutes. Perhaps your error comes in the fact that 1 day is not one rotation of the earth, but instead one rotation in the earth-sun rotating reference frame? Tom Ruen (talk) 09:47, 27 November 2013 (UTC)
 * This webpage comes to the same number as me. I'll adjust the text. Tom Ruen (talk) 09:52, 27 November 2013 (UTC)
 * And quiz 2) On average the Moon rises how many minutes later each day? ANSWER 50.47 (Divide 1440 (minutes in a day) by 28.53 to get the answer.  The latter figure is the average number of times the Moon rises during a synodic month.  It is one less than 29.53 because the Moon laps the Sun every synodic month.)
 * Tom Ruen (talk) 10:05, 27 November 2013 (UTC)

Hi Tom. I'll explain. Using the synodic period of the moon is a changing reference for the moon's orbit. As earth moves in its orbit (for that day) the angle to the sun changes. This is a changing reference. I see so many pages with this reference. Earth is under constant radial acceleration about the sun and pointing to the sun as the reference for "Going-Around-the-Earth" is a constantly changing vector. This is not an inertial reference. Therefore, the position of the moon "Around" Earth is being based on a moving reference and therefore not on a 'stationary' (or nearly so) inertial reference. Moon-Rise is not determined in any way by the position of the sun relative to earth - NONE. [Sun direction *does* effect moon-phases, but NOT location of moon relative to EARTH] When the moon goes the oft quoted 29.5 DAYS [corection] it has actually traveled around Earth once PLUS the amount (angle) Earth moved in its orbit during that time. Draw out a "top view" of the two positions of Sun-Earth-Moon in both positions a day apart (or more for clarity) and it should be clear that Moon went more than one rev. when you have the Moon-Sun angle the same for both. Using the Siderial moon-period references the position of moon to Earth to a much more close-to-inertial reference (background of stars). Any motion of the background of stars or our galaxy is much less an effect, so is neglected here.

Then, so many folks note that after 24 hours, the moon is 12 (actually 13.18) degrees below the horizon, then proceed to calculate how long it takes for Earth to rotate that amount TOTALLY IGNORING that the moon DID NOT stop and wait for Earth, but is still moving. Therefore, the moon moves further, in smaller amounts if you keep trying to calculate these additional catch-up times. The simplistic divide X by Y calculation implicitly assumes that the moon stops to wait for Earth to catch-up. If you doubt this reasoning Google for "How much time does it take for the minute hand to catch up with the hour hand" This is exactly the same problem and Rotating the clock to lie on its side, will not change it. It takes MORE than 20 minutes for the minute hand to catch-up with the hour hand starting from 4:00. Same thing. Using the two speeds and D=RT you come to the correct solution. If someone has a logical response that refutes this, I want to see it. I have given this considerable thought and also have emails to several astronomy profs... Some of them even have this error on their web page! Blows my mind, it seems so obvious. As a side note, using the moon's crossing of the observer's meridian should be a better guage for this analysis than moon-rise. It shouold remove, or at least minimize any observer-latitude effects., but conceptually moon-rise is ok. Otherwise I agree that 50 is approximately 54.70779267...&#32;-- Steve -- (talk) 20:13, 27 November 2013 (UTC)

That should have been 29.5 days not degrees. &#32;-- Steve -- (talk) 20:27, 27 November 2013 (UTC)

Ahhh! Tom, I just caught another thing you mention. I am pleased you try to question the 24 hour earth-day being a synodic interval, rather than siderial and a possible source of error in the time scale. It shows that you have, perhaps, better than average grasp of this issue. I find it interesting/puzzeling, however, that you know that one rotation of Earth is the Siderial 'day' (not the common Synodic 24 hours), Yet maintain that one revolution of Moon is the Synodic period...? That right there is the key to getting this correct! However, NO. I have not made any such error and have anticipated that exact question. The basis for our units of time is indeed the synodic Earth period. However, ANY constantly advancing time scale can be used regardless of how big the units are. We could just as easily have used a siderial Mars-Day, divided it into 25 'Mars-hours' and those into 50 'Mars-minutes" and arrived at the same conclusion... Then, get the same number after converting back to Earth minutes.  This would be no different than measuring in meters, then converting to inches.  The key to my claim is realizing that Moon orbits *must* be in a SIDERIAL reference, not Synodic (Sun referenced).  Please consider carefully. Regards, &#32;-- Steve --  (talk) 20:57, 27 November 2013 (UTC)

Tom, Your link above to cs,astronomy.com appears to have rotted. &#32;-- Steve -- (talk) 21:09, 27 November 2013 (UTC)

While I feel that my calculations are completely valid and have been validated by the clock hands catching-up algorithm described on several pages on the net, I think that my calculations may be considered to be original research and I will simply upload my complete analysis to my web site for others to review and back off here. I invite review of my method as I see so many duplications of the common errors and simply want to provide the correct view. I also realize that this may seem either pedandic, or like someone with little understanding of some fundamentals who is trying to force an invalid, though well meaning idea on others, but the aforeto mentioned validation as well as the sound reasoning behind my proposed correction encourage me to continue this quest. I am also contacting several astronomy instructors and professors with this for review and appear to have in the works an analysis of this by a group of advanced astromony students at one university. I also think this subject probably belongs in the Orbit of the Moon Wiki page or integrated into the Moon Project in some way. Regards, k9dci at arrl.net  &#32;-- Steve --  (talk) 02:14, 28 November 2013 (UTC)


 * Sorry, I can't explain your error. I wrote my own astronomy program, and just tested viewing every 24 hours, 50.47 minutes, and the moon stays near the same sky azimuth, moving in a nice analemma pattern, a figure-8, moving north and south due to the orbital inclination, all as expected. Whatever answer you need, you'd better find your own calculations to match the corract 50.47 minutes average shift. Tom Ruen (talk) 02:44, 28 November 2013 (UTC)


 * OK tom. Thanks for responding.  I'm sure it was considerable work, but since it is your code, I assume you ptobably use the Synodic moon period.  Can you simply change it to the Siderial to see what the number scomes out to?  My only possible, but unbeliveable doubt if any, is basing the time on the Siderial moon-period, but at least one site i found so far validates that.  Until someone can clearly explain why the calculation must use the synodic, I still feel my algorithm is impecble as validated by the clock hands algorithm.  I am not sure (convinced) that the presence of an analemma is alone a sufficient proof that everything about your algorithm must be correct.  If you could report the effect of only going to the Siderial moon period, I'd really appreciate hearing if it goes hay-wire or still looks reasonable (keeping the analemma and all other salient behaviors)  When I put the 29.53 synodic in my calculator (Excel) I get 50.47318612, so you are indeed using the algorithm that (at least math-wise) implicitly assumes the moon stops at 24 hrs waiting for Earth to catch up.  That is what my math does to get that number.
 * I just can not see how synodic is the correct basis for the position of the moon relative to the earth. Good ole' Sol has no standing as I can see. If it wasn't so cold, I'd really be tempted to take out the scope and reticle eyepiece and let it sit over-night pointed at a moon crossing spot... I think a meridian crossing should do it for one cycle. If you celebrate it, have a nice holiday. Regards, &#32;-- Steve --  (talk) 03:47, 28 November 2013 (UTC)


 * I'm sorry. I have no degrees of freedom in my calculations. Tom Ruen (talk) 04:09, 28 November 2013 (UTC)


 * OK tom. The program you wrote sounds impressive and I'm sure took much time and it appears to include the accentricity and/or orbit plane offset, so it shows a nice analemma.  I still can't get to that web page, and I have yet to find one that is 100% correct.  I know that sounds fishy, but I now have no doubt I am correct.  Since the number: 28.53 is based on the synodic month, it is the wrong number for 'lapping' the earth. At least the following guy figured out the issue (in last paragraph), even if he couldn't get there and also uses the wrong moon-period.
 * http://myscientificbluff.blogspot.com/2009/03/why-moon-rises-50-minutes-later.html
 * I'll be candid.  I'm sorry you can't change your program to correct it if you used the numbers and calculation you show here.  If you synch it to the real moon it will be off by about five minutes a day.  I *can* explain the error and it is the formula that so many use, including you.  It (24/29.5) only calculates how far the moon moves in 24 hrs {IF it had used Siderial}.  The time it takes Earth to get to THAT spot (52.7 min) is time during which the moon is still moving so it won't be there.  It didn't stop at 24 hrs.   Also, the calculation requires the Siderial time.  Think it through step-by-step carefully and it should be obvious.  I'm in contact with an Astromony professor who will review my work and if you contact me, k9dci at arrl . net, I'll send you my draft paper explaining it fully, including why I think so many people are fooled by the other divide formula.  It is not very difficult.  Cheers &#32;-- Steve --  (talk) 02:35, 29 November 2013 (UTC)
 * P.S. I am currently taking Moon-rise times from the Naval Observatory for a year and will calculate the average (for a point on the equator in hopes that location will minimize the variation due to the axis difference/eccentricity) and will report what correlation I see.   If I am, I'll admit I'm wrong, but I surely can't see where it could be..... Regards, &#32;-- Steve --  (talk) 04:02, 29 November 2013 (UTC)


 * Tom, I'm crushed! (-) My result is clearly inconsistent with USNO. They can't be off, for sure!    Well, I'm glad your number is good and quite perplexed why my result is so far off.  Thanks for bearing with me.  I was getting uncomfortable after hearing about your program. That kind of effort certainly had to be based on sound information... It took considerable fiddling to parse time from the text file of four digit 24 hour times, but from the U.S. Naval Observatory data (to the minute) for all of 2013, on the equator, at 88 West; the average sunrise shows as 50.51559145.   Perhaps I should call them for the answer...   I hope this wasn't annoying to others watching.  Man! I haven't had such a failure in a long time.
 * Max month avg=51.207 Min month avg=49.931
 * Pretty nice agreement... I averaged each month then averaged the monthly averages, but each month's average was close as well.
 * Someone explain why first year Algebra didn't work...?
 * Arg... Regards, &#32;-- Steve --  (talk) 05:50, 29 November 2013 (UTC)


 * I'm glad you confirmed it, maybe you can still figure out why. My program is based on [ http://www.amazon.com/Astronomical-Formulae-Calculators-Jean-Meeus/dp/0943396220 Astronomical Formulae for Calculators] by Jean Meeus. But my calculations were based on first year algebra: (t-1)=t/p, where p=period of moon's revolution (29.53d), 1 day=period of earth rotation, both periods relative to the direction of the sun, and t=time. Have fun! Tom Ruen (talk) 13:10, 29 November 2013 (UTC)


 * I can't let this go until I do!  Let's hear it for waking up with an idea...sorta'  I 'know' the Algebra is correct, so I started doubting the input data & found I had used Earth Synodic period.  Your comment above, about that, didn't "click" because (A - time is time, but more importantly, B -) I was too focused on the correct Moon-period and seeing (what appears to be) the synodic moon-period number in everybody's formula had, and sill does have be obsessed with why that looks oh-so wrong.  Trouble is, Earth synodic is barely 1/3% different from Siderial and I'm 8% high Not-To-Mention-The-Fact-That fixing that goof moved me even further/later! "Speeding up" the Earth should shorten the rise delay! Arrrrg!  Now, I doubt the emplementation in the spreadsheet and will start from scratch and carefully "design" that better.  Forgive me, I'm an Engineer...(ret).  Happy you are correct, that you see the analemma, and that I know what an analemma is! (a engineer-friend talked about the one typically seen on globes, not too long ago) Cheers. &#32;-- Steve --  (talk) 15:20, 29 November 2013 (UTC)


 * Tom, I've averted a distaster for mankind! The universe is no longer going to implode!  " 50.62676198 ". +.22% error per USNaval Obs.  Not bad... I already had a fresh spreadsheet calculation for which the Earth-Siderial change fixed. I always have checks in my spreadsheet calculations and this just happened to perpetuate errors.  Murphy!  Then, I found that I had too many "24"s sprinkled throughout the original spreadsheet formulas, instead of referencing the actual Earth period.  Thanks for sticking with me.  I now know I understand this from a pure physics standpoint.  I think this shows me that the oft quoted formula of "24/29.5" is *STILL* not only the wrong calculation, but that it is only an accidental close call - It is close because the Moon is relatively slow so using Synodic in what I call the "Stopped Moon Formula" comes close, but I'm steering clear of the analemma...other responsibilities call. Quoting myself: "They say that we learn by our mistakes.  BOY! are we LEARNING NOW !!!  (-)
 * P.P.S. The delay at Equator over 2013 ranged from 43 to 64 minutes (to the minutes shown by the Naval Obs) - I assume their data is to the 'nearest' minute.  Cheers, Steve  &#32;-- Steve --  (talk) 16:32, 29 November 2013 (UTC)

Tom,  I reviewed how you reworded the daily delay part. I guess it's ok. I finally got to that cs.astronomy site (router goofy), but those numbers aren't there in a Sept 12 "Harvest Moon" blog. Also poked around Curt's site a bit.

A - I believe you have a typo in that quote: "(1440/28.53 _hours_, or the number of _hours_ in a solar day ...) 1440 is # of _MINUTES_ in a solar day thus making the final units also _Minutes_(per day). Or is that his typo?

B - RE: "the number of solar days it takes for the moon to orbit the earth" If I understand the words, it is saying:  "Earth (Synodic, or human observable) days per Lunar orbit (the true sidereal orbit)"    is simply the moon's sidereal period (in regular days)...which is 27.32 Earth-Sun days. That's what I get from the words you posted... another typo?

C - Does/did Curt explain the derivation of the 28.53 number? That looks fishy to me. The true calculation for two uniformly moving bodies is not a simple ratio -it has a difference in it that is the difference in speeds; more easily thought of as a "closing velocity" like one car tailing another. Regards, Steve   &#32;-- Steve --  (talk) 03:49, 30 November 2013 (UTC)


 * Yes, the ref-block comment didn't make sense, was left over too quickly from the original wrong explanation. I changed it now, just left the calculation (1440/(29.53-1)=50.47 minutes. Its hard to explain simply in words, as all the above commentary confirms. You could write speed motion equation: earth e(t)=a*t, moon m(t)=b*(t+1), starting time t=0 after first day, so then e(t)=m(t) --> a*t=b(t+1), t(a-b)=b, t=b/(a-b), where a is speed of earth 1 turn/1 day, and b is 1 turn/29.53 days. So you get t=(1/29.53)/(1-1/29.53) = 1/(29.53-1) = 1/28.53 days = 24/28.53 hours = 14400/28.53 minutes. If all that helps!? It would be nice to link to a webpage that explains that, but I don't think wikipedia ought to be explaining every calculation included, but a formula is nice when simple. Tom Ruen (talk) 04:12, 30 November 2013 (UTC)


 * Grast! Thanks. Couldn't see any of that on Curt's Page. Copied it and will chew on it later.    I did it differently, but may be equivalent.  TO get to next catch-up pint, Moon moves X distance, Earth moves 360 + X.   Then use appropriate angular velocities in the D=RT uniform motion equations and solve symultaneously for time.... I wonder if it is an issue with the "original work" restriction.  They like "outside" references.  I can't add my web page or a paper I wrote as a reference, but someone else can.  Regards,   &#32;-- Steve --  (talk) 05:44, 30 November 2013 (UTC)


 * Here's a book reference with 50.47 also . I'm sure a better (original) source can be found with some effort. Tom Ruen (talk) 04:04, 1 December 2013 (UTC)


 * OK Thanks. Believing that number is no longer the issue.  I understand and set up your algorithm in Excel.  I want to try to understand a little better rather than just stopping with something that works.  I've been trying to do it in the sidereal frame and the algo I came up with is still bad. Because the moon moves so slowly, the difference I am seeing is too small to get a handle on why I can't set up the equations properly.  I devised an earth-moon system with a faster moon to be able to get a bigger difference between algorithms and to possibly help to zero-in on the issue.   I first worked out the Synodic and siderial data, now I'm trying to visualize the set up for the sidereal equstions, but it looks quite a bit more complex than Synodic.  I'll play a while more before giving up on one of the methods.  The method based on the difference in speeds (closing speed) appears to work in siderial, but I have to carefully look at things.  It's a quest, now, but that's normal for me.  regards, Steve &#32;-- Steve --  (talk) 05:18, 1 December 2013 (UTC)


 * It is interesting that book reference calls 24h 50.47m a "lunar day", meaning if the sun didn't exist, and the moon was our source of light, this would be the period we'd call "day". So a second way to compute this is based entirely on the 27.3217 moon orbital period, and 86164 second (0.99727d) sideral day. so the (relative) synodic period = 1/(1/p1-1/p2)= 1/(1/0.99727 -1/27.3217) = 1.0350488 days or extra 50.47 minutes again. Tom Ruen (talk) 06:01, 1 December 2013 (UTC)
 * It turns out that my calc is the same as yours. My brain was thinking (trying to) in sidereal, but I wound up doing an equivalent synodic solution.  I started with the same uniform motion eqn's, but said For Moon, D is "x" and for Earth D is 360 + "x".  At the end a day needs to be subtracted since "x" is the day plus the delta. Then Algebra did the rest, as it should - no matter the starting point.  For some reason I'm hooked on the concept of only using sidereal numbers to start...  I gotta' get this resolved in my brain so I can move on to other things...   That lunar day is interesting and may provide a link to where my brain wants to get. I am still getting my 'constructed planet-moon' system firmed up so it is easier to 'see' when the periods line-up again.  I'm working with something like a 10 day sidereal year and a 4 day moon sidereal period (-) P.S. when I started this thread by changing the number, I came on pretty convinced I had it right and the old formula made me think anyone standing up for it wasn't very experienced, so had you said you used the complex algorithms earlier, I'd have realized that I was probably already in trouble with my calc. and backed off.  Sorry to have sounded like a ...   I crashed and burned on that one...but have a deeper understanding, or will,  because if it.  Thanks for sticking in there. P.P.S.  I don't know if thread this is Wiki-apperpriate, but as long as nobody compains, I'll report progress. In a few weeks I have an plan set to talk with the Astro professor about making this a student project of some kind. Regards, &#32;-- Steve --  (talk) 17:49, 1 December 2013 (UTC)
 * This thread isn't quite on-target, but can be archived sometime. Incidentally, I see my formula, synodic period = 1/(1/p1-1/p2), is at Synodic_period. Tom Ruen (talk) 18:01, 1 December 2013 (UTC)
 * But, per the wording?, that's two bodies (planets) around a third (star). Not one body (planet) and its moon orbiting the first body (planet)  .. party of the second part...&#32;-- Steve --  (talk) 22:10, 1 December 2013 (UTC).
 * OH, I think I see your point. One of the two orbiting bodies is our moon and the other is a point on the surface of Earth - sure. This is precisely the difference in velocities (closing speed) I have mentioned. Given that speed (Degrees per/minute) and the separation (in degrees) the time to collision/intercept/moon-rise is simple.  That's the easiest way to visualize taking care of the issue that the moon is still moving after the initial 24 hours, so it takes longer that just how long Earth takes to get to the 24 hour location of the moon.  Regards,      &#32;-- Steve --  (talk) 22:27, 1 December 2013 (UTC)

Whew! I identified what appears to be the source of my original error in stating the delay as 54.7078 minutes. That number actually appears to be correct, but... The calculation I derived and used is algebraically identical to the one you showed using synodic values and the closing speed method. What I missed was that I actually solved for the time after Earth's _sidereal_ day that it takes Earth to catch the moon again, not after the solar day. Subtracting the interval from sidereal to synodic day gets to 50.776 minutes (0.61% high). It seems that it should give the same exact result, but I am unable to say why it is not precisely 50.47. I can only guess that it may have something to do with the way the periods are defined - since there are difference ways to define a period that is not constant, but varies due to orbit eccentricities and eccentricities of the bodies the times are related to. After all, this is unreasonably trying to calculate a precise average for a quite complex set of interrelated rotations. An exact approximation... (-) Regards, &#32;-- Steve -- (talk) 04:48, 9 December 2013 (UTC)

Harvest and Hunter's moons and hemisphere
The "Harvest and Hunter's moons" section currently says:
 * "Harvest Moon" and "Hunter's Moon" are traditional terms for the full moons occurring in autumn, usually in September and October, respectively.

However, autumn is only around that time of year in the Northern hemisphere. So, are these the full moons around the September equinox, in which case the hemisphere doesn't matter, or are these the full moons around the autumnal equinox, which makes them in September or October in the Northern hemisphere and in March or April in the Southern hemisphere? To put it a different way, counting both hemispheres, are there one or two hunter's moons per year? The way the above line is currently worded is pretty much self-contradictory on this point. -- Hi  Ev  13:00, 28 December 2013 (UTC)

Assessment comment
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Backscattering yields a uniform full moon image.
urila — Preceding unsigned comment added by Urila (talk • contribs) 02:08, 31 July 2018 (UTC)

The Scattered light is considered in the literature as a diffusive light, light that passed a number of scattering events before it left the scattering material. Diffusely scattered light must obey Lambert's Cosine scattering law. In the case of unidirectional light scattered backward from a surface of a sphere, the meaning is maximum scattering intensity in the middle of the sphere, and a decline to zero toward the periphery by the cosine law. The full moon looks uniform and people continue to assume that the light is diffusely scattered from it. More than that. The nearly uniform sphere image is common to all the planets and their moons, including the earth as observed from space and the moon. Out of thousands upon thousands of true photos, there is no single true photo that obeys Lambert's Cosine law. The only photos that do obey the law are rendered photos, photos that are at least partly simulated. Contrary to all that, if the scattering is assumed to be mainly a single event, then all the scattering dipoles are directly stimulated by the light radiation on the illuminated scattering material. Then scattering by them must be coherent, and then the full moon and all the other illuminated bodies, with similar illumination geometry, must be uniform, at least approximately. The full moon tells us that single event scattering is dominant. Maybe with small corrections of multiple scattering. Why is the single event dominant? It seems that the effect is geometrical and statistical. If we consider one event scattering, two event scattering, multiple event scattering, then the event probability will decline with an increasing number of scatterings. The single event has a probability of at least 50% and it is the strongest event. Nearly all the background that surrounds us is a singly scattered light. A true diffusely scattered light is rather rare. Urila (talk) 15:35, 27 October 2020 (UTC)

Urila (talk) 03:58, 15 May 2020 (UTC)

180° apart?
So the article said it was 180° apart. It's not exactly true on every full moon, except for lunar eclipse, though it's still called full moon. I corrected it a bit and some users reverted me. The only reason why it's not exactly 180° apart on every full moon is that moon orbit is 5° tilted from earth orbit. The Channel of Random (talk) 16:00, 13 August 2019 (UTC)


 * You can find the official definition here (see p. 478). AstroLynx (talk) 16:09, 13 August 2019 (UTC)

When I say it's not exactly 180° apart I mean it's few degrees away north or south. The Channel of Random (talk) 18:10, 13 August 2019 (UTC)


 * You are referring to the angular difference between the Sun and the Moon as measured along a great circle on the celestial sphere which at astronomical full moon is indeed usually slightly less than 180°. But for the computation of the moment of the astronomical full moon this is irrelevant as only the projected longitudes of the Sun and the Moon on the ecliptic are considered. This is how astronomers have computed these times for more than two millennia and it is by far the most straightforward way to do this. The lede already clearly mentions that ecliptical longitudes are involved and changing 'exactly' to 'approximately' is simply wrong. Further on, perhaps in the 'Formula' section, it may be useful to elaborate on this distinction and on the paradox that an exactly fully illuminated moon is actually never seen as it is then in the Earth's shadow cone. AstroLynx (talk) 07:13, 14 August 2019 (UTC)

A Commons file used on this page or its Wikidata item has been nominated for deletion
The following Wikimedia Commons file used on this page or its Wikidata item has been nominated for deletion: Participate in the deletion discussion at the. —Community Tech bot (talk) 03:52, 26 January 2020 (UTC)
 * Lunar eclipse January 31 2018 California Alfredo Garcia Jr mideclipse.jpg

Two meanings of "full moon" conflated
Reading the current lead is really odd:

"The full moon is the lunar phase when the Moon appears fully illuminated from Earth's perspective. This occurs when Earth is located between the Sun and the Moon (more exactly, when the ecliptic longitudes of the Sun and Moon differ by 180°).[3] This means that the lunar hemisphere facing Earth – the near side – is completely sunlit and appears as a circular disk. The full moon occurs roughly once a month."

So, in the first sentence a full moon is described as a lunar phase, meaning it is a period of time lasting several days (around 7.4 days according to the Lunar phase article).

But in the following sentences a full moon is described as a point in time where something specific happens, thus with no time span whatsoever. (The descriptions are rather lax, though, with stuff like "completely sunlit" (which can logically never happen, as then we have a lunar eclipse, a solar eclipse on the moon), so the descriptions about the point-in-time full moon should also be clarified).

So there are two separate and quite distinct, although related, meanings of the words "full moon", but they are mysteriously conflated without even mentioning that they are two distinct concepts. That's really odd.

Anyway, it should be fixed. I'm just unsure of the proper Wikipedian way of writing the lead in an article about two distinct, but closely related, concepts with the same name.

--Jhertel (talk) 23:10, 30 September 2020 (UTC)


 * Full moon never means a quarter cycle. It can mean 3 nights in a row but not 4. Or sometimes an instant or a single night or date even though the shape is the same to 20/20 eyes for 2 or 3 nights in a row. It's usually easy to tell exact night since rising in day means before full or almost and rising 50 minutes after sunset means a day after full on average but that's position not shape. Sagittarian Milky Way (talk) 23:55, 30 September 2020 (UTC)


 * Thanks for your reply, Sagittarian Milky Way; I feel humbled talking to a galaxy. Well, you mentioned your personal opinion about what a time-spanned full moon is (one of the two distinct concepts), and that's then a different definition than the definition stated in the first sentence of the lead. What the time-spanned full moon exactly is is then up for discussion and finding reliable sources for the different opinions. I should mention that your opinion of the definition of the time-spanned full moon is quite close to my sense of it (I have a sense of 1-5 days), but that really doesn't matter, as we have to keep our personal opinions away from Wikipedia and stick to facts (that is, which person with what education said what, based on which observations, written in what source).
 * But the primary issue I mentioned is that there are two clearly distinct concepts here, conflated silently into one. A time-spanned full moon (several days) and a point-in-time full moon (exact point in time). (Forgive my wordings; they are just simple attempts to put words on the two concepts to distinguish them, and English is not my mother tongue). The point-in-time full moon can be clearly defined, but the other cannot and will be a matter of differing opinions which can then be discussed in the article. I just don't know how to structure an article about two closely related, but also clearly distinct concepts with the same name. --Jhertel (talk) 23:43, 1 October 2020 (UTC)


 * You are correct the other one is fuzzy, I tend to think if you can see gibbous without magnification that makes it not full and I've heard the 2 or 3 but not 4 thing from somewhere but don't remember where. If exact full is too near noon then only 2 nights, if exact is near midnight then 3 nights. A low enough latitude is implied but not mentioned by whoever wrote this and some might be sharp-eyed enough to break this rule of thumb so it's fuzzy. Now change of illuminated percent in an hour rapidly accelerates with increasing distance from the umbra center for some days after full so atypical human eye sharpness doesn't pin it down as much as it might seem but again still not exact science. Personally 5 days total is about where I'd call it close to full or full instead of just gibbous but that has no source whatsoever. Sagittarian Milky Way (talk) 01:42, 2 October 2020 (UTC)

Addressing the definition of a full moon
The Full Moon is what we see when the Earth facing side of the Moon is at its maximum visibility as seen from Earth during a given orbit. I say that because it’s orbital inclination is approximately 5.145° which means in almost every case, we never see a 100% visible moon during a full moon.

That can only occur during a total lunar eclipse and being at the right location at the right time. For that to happen, one must be at the right location at the right time and the Moon must be within the right latitudes around the ecliptic.

While the average person might not visually tell the difference between a moon that’s 96%+ or 100% full with unaided eyes over the span of several days/nights (save for lunar eclipses which appear dark due to Earth’s shadow and red due to atmospheric light refraction), it’s obvious for those with sharp vision and/or optical equipment.

Yet the photos obviously show the Moon’s Earth-facing side not being completely sunlit as either the east, west, north or south of the Moon is hidden in darkness as those portions aren’t reflecting any sunlight.

All in all, the term full moon appears to be a misnomer in most cases as it’s only truly possible if viewed at the right location on Earth at the right time during the right lunar eclipse.

The article needed a big fix as it stated something we almost never see. It would be more common to see a 100% full moon from a given location on Earth if it’s orbital inclination were 0° relative to the ecliptic. Yet as written far below the page, it’s a moment that never lasts. 67.235.204.246 (talk) 10:14, 29 January 2022 (UTC)

"Harvest moon" listed at Redirects for discussion
An editor has identified a potential problem with the redirect Harvest moon and has thus listed it for discussion. This discussion will occur at Redirects for discussion/Log/2022 July 15 until a consensus is reached, and readers of this page are welcome to contribute to the discussion. Chris Cunningham (user:thumperward) (talk) 19:42, 15 July 2022 (UTC)

Dark spot during no lunar eclipse
It says there’s still some dark spot when there isn’t a lunar eclipse.

Well first of all, a spot is a point, and second of all, how much of it that appears dark during a full moon depends not only on where the Moon is in its orbit, but where you’re viewing it.

The only way you can’t see a dark section during a lunar eclipse is if the Moon is at the very center of the anti-solar point (the opposite of the Sun’s position), which rarely ever happens and you have to be at the right place on Earth at the right time. Even during an ultra-central lunar eclipse, very few places will ever see the moon apparently making a bull’s eye with the anti-solar point even though it hits the center of Earth’s shadow no matter where you are during so.

You gotta think about parallax and how the Moon is much closer to Earth than even the nearest stars (including the Sun), so where it is relative to background points in the sky varies depending on where you view the Moon from.

Yet diurnal libration (caused by Earth’s rotation) also adds to the fact that only limited places get such spot on views of the Moon during ultra-central lunar eclipses (where the portion unilluminated by sunlight of any means) is too small for even high quality digital cameras to detect.

Truth to be told, the “spot” that isn’t illuminated by the sun never disappears from view unless you’re at the right place at the right time during a lunar eclipse. Eric Nelson27 (talk) 13:39, 25 July 2022 (UTC)

particularly where you are during any total lunar eclipse. Central, even more so Eric Nelson27 (talk) 13:42, 25 July 2022 (UTC)

Wiki Education assignment: Research Process and Methodology - FA22 - Sect 201 - Thu
— Assignment last updated by WZ2372 (talk) 14:19, 8 December 2022 (UTC)

North American names
I've added material (with references) for full moon names attributed to indigenous North Americans. There's quite a lot of information, and given the limited geographical scope (and the dubious nature of some of the sources), I wonder if there should instead be a separate new article for these folk names. The material I've added is in the section headed "Farmers Almanacs", which again seems out of place, since the Maine Farmers Almanac claimed its 1937 list was of traditional English names (though they were neither traditional nor English). I also think that the big table of moon names in that section should be removed, since all it shows is that various authors have suggested lots of names that are not well substantiated. Cheeselymoon (talk) 21:33, 27 April 2024 (UTC)


 * The links in the article lead to hundreds of Native American full moon names (see e.g. http://americanindian.net/moons.html). This makes the table of names redundant as well as potentially misleading, since it lends a false air of authority to Beard and the Farmers Almanac, both of which are dubious sources. So I'm going to remove that table - and if anyone disagrees they can undue the revision and put it back. Cheeselymoon (talk) 20:34, 29 April 2024 (UTC)