Talk:Equinox/Archive 2

Easter
Read this from the Cultural Aspects section:

"The Christian churches calculate Easter as the first Sunday after the first full moon on or after the March equinox. The official definition for the equinox is on March 21. However, as the Eastern Orthodox Churches use the older Julian calendar, while the Western Churches use the Gregorian calendar, both of which designate March 21 as the equinox, the actual date of Easter differs. The earliest possible Easter date in any year is therefore March 22, on each calendar. "

The official definition of the equinox is March 21? Wrong. Look at http://www.msnbc.msn.com/id/7231497/

Therefore you would need to reconsider the earliest date for Easter; it may be earlier than March 22.

Mdoc7 (talk) 05:33, 21 July 2008 (UTC)


 * The 'official' definition of all churches is that the equinox is March 21. Churches do not use the astronomical definition. I'll clarify this paragraph. — Joe Kress (talk) 05:12, 22 July 2008 (UTC)


 * Your "all churches" is untrue. The UK, hence the US and the Church of England, etc., does not use the term "equinox" in defining Easter; it just uses that fixed calendar date. 82.163.24.100 (talk) 20:34, 21 October 2008 (UTC)


 * The equinox date is not an astronomical date. In 2016 that date will be March 19.  Read the article.  :)  Mdoc7 (talk) 18:00, 23 July 2008 (UTC)


 * The church equinox is the whole day designated March 21. The church ignores the astronomical equinox, no matter on what date it happens to be. That was the primary reason for the reform of the Julian calendar by Pope Gregory in 1582. The church equinox remained on March 21 whereas the astronomical equinox had shifted to March 10-11. — Joe Kress (talk) 18:42, 23 July 2008 (UTC)


 * Perhaps a better wording would be "The date of Easter for Christians was set by the first Ecumenical Council at Nicea (325 AD) as - The first Sunday following the Vernal Equinox and the full Moon, with the date of the Vernal Equinox set at march 21st by that same council. Some countries have set different dates for Easter". However the best solution it seems to me is to link to religious, cultural, and/or historical pages for this discussion and keep this page purely about the current state of scientific knowledge. — Preceding unsigned comment added by DimasD (talk • contribs) 11:19, 21 March 2014 (UTC)

Passover
The article currently has : The Jewish Passover always falls on the full moon following the first new moon after the northern hemisphere vernal equinox. That cannot be exactly and perpetually true, assuming that the present Hebrew calendar is maintained. Pesach is on a fixed day of a fixed month of the Hebrew Calendar. The Hebrew Calendar Year is longer than the present Mean Solar Year, to which the Gregorian Year is a better approximation. Therefore, Pesach must, long-term, drift with respect to both the Astronomical and the Nominal Equinox. And, by convention, the Vernal Equinox is in March, even in Australia. 82.163.24.100 (talk) 20:34, 21 October 2008 (UTC)

The Hebrew Calendar year is 12 Lunar Months but every 3-4 years or so there is a 13th month which fixes the drift, I'm not sure but I think it's more like Pesach falls on the first full moon after the vernal equinox, but only sometimes the equinox falls before the new moon (Rosh Chodesh Nissan) before pesach — Preceding unsigned comment added by 89.240.39.86 (talk) 21:34, 13 October 2012 (UTC)

In regards to the Passover and the events surrounding it that are commemorated by the Hebrews and the Christian church, unfortunately both calendars are in error according to the Bible they both base their beliefs upon. Please don't get me wrong, it has only been recently that the error became clear to me also. According to Exodus 12:1-2 and the surrounding passages Israel left Egypt during the first month of the year. According to Numbers Moses, two years later sent spies into the land of Canaan during harvest time, in fact when the spies came back after 40 days  they brought with them fruit that ripens at or near the time of the fall equinox. Not only grapes, but they brought figs and pomegranates, early fall produce. Therefore it is obvious that the Passover, (which Israel would have kept a few days later if they would have gone in) and the death and resurrection should be observed at or near the time of the fall equinox. The earth was created three days before the sun, the sun was placed on an angle to the rotation of the earth thus the first equinox was on the forth day. Since we are plainly told in the preceding passages from Exodus, Numbers and for that matter Joshua that the year begins at or near the fall equinox, it is my contention that the world was created just before the first fall equinox. That being the case, the flood was over at the time of the fall equinox. The children of Israel entered Egypt at the time of the fall equinox. The children of Israel left Egypt at the time of the fall equinox. The crucifixion and resurrection took place at the time of the fall equinox.108.98.156.66 (talk) 23:38, 13 September 2014 (UTC)Donald Vander Jagt

Merge
Per previous discussions at, Fall equinox, Autumn equinox, , September equninox, March equinox, and currently at WT:AST, these three pages should be merged together. (and perhaps some unmerged material left over at the redirects from spring and autumnal

-- 70.24.250.110 (talk) 00:34, 1 December 2012 (UTC)

did you now that equinox means equle night — Preceding unsigned comment added by 108.219.37.239 (talk) 04:47, 12 February 2013 (UTC)
 * equinox – Wbm1058 (talk) 19:57, 6 March 2013 (UTC)


 * Comment – The above referenced WT:AST discussion is archived at Wikipedia talk:WikiProject Astronomy/Archive 11. – Wbm1058 (talk) 20:57, 6 March 2013 (UTC)

I think the only thing that needs to be done is: explain that the vernal equinox is the spring equinox, or, the March equinox; and the autumnal equinox is the fall equinox, or, the September equinox. You provide a link for solstice but not for equinox; that would help. Otherwise, this subject is huge and very confusing; I would leave it as is, otherwise. Sharon Elizabeth Creamer. — Preceding unsigned comment added by Sharon6756 (talk • contribs) 23:15, 22 July 2013 (UTC)

Explaining the different equinoxes (equinoxi?) would be a good thing for this article, and either links or a merge would be good. I'm leaning towards links. 216.188.202.10 (talk) 14:15, 20 March 2014 (UTC)


 * Strong Oppose - Do not merge. They may appear to be similar, but the equinoxes are different nonetheless, and should be kept as separate articles. 72.197.234.162 (talk) 07:13, 3 May 2014 (UTC)

Not to be offensive
but this is English Wikipedia and the equinoctes (equinoxes) aren't known by their Chinese names at all, so i'm going to delete that. there is already a separate section on the equinox in East Asia therefore it is redundant to state that information twice ==

also, when the author states "The least culturally biased terms." that statement is not cited, and sounds like original research, and seems like something an SJW would dream up. — Preceding unsigned comment added by 24.254.240.91 (talk) 17:21, 23 September 2014 (UTC)

Ten, not nine days
In the article, as it is now (January 12 2015), it is claimed that the Gregorian calendar reform left the superflous leap day AD 300 unaltered, but the Gregorian calendar reform removed ten, not nine superflous days in 1582 (reforms occuring after February 24 1700 eleven days). Will someone please explain this more clearly.81.236.219.119 (talk) 02:53, 12 January 2015 (UTC)


 * Good question. According to the table in this article, the Julian and (proleptic) Gregorian calendars do not match up in AD 325, they are one day off.  So apparently they jumped ahead one too many days in the conversion.  Don't know if this was a simple mistake, or if there was some rationale behind it.  --Lasunncty (talk) 08:51, 12 January 2015 (UTC)


 * It seems unlikely that one of the best astronomers of his time made a mistake even a secondary school pupil would be able to spot. I have only a guess about a solution, and no text sources for this, but is it possible that the Equinox Tables used in Alexandria in AD 325 could have been composed before February 24 AD 300, thus giving correct information about the vernal equinox in late third century, rather than early fourth century? If the intentions in 1582 were to synchronise calendar dates and equinoxes as given in these Alexandrian Tables, this could be a solution. Any other possible answer to this riddle?81.236.219.119 (talk) 13:29, 12 January 2015 (UTC)

Declination of Sun
The article says "An equinox occurs when the plane of Earth's Equator passes the center of the Sun"; I'm not an expert, but that doesn't seem right. The earth's equator plane is at all times tilted 23.5 degrees with respect to the earth's orbit around the sun. The earth's equator plane would never, ever, "pass through the center of the Sun". Could a true expert educate me if I'm wrong? Jssprojects (talk) 21:46, 14 January 2015 (UTC)


 * In astronomy the spring equinox is defined as the moment when the apparent geocentric longitude of the Sun measured along the ecliptic is 0 degrees. Many people claim that the apparent declination (angle from the celestial equator) is then also zero but although this is very nearly true an exact computation will show that there always is a small difference. AstroLynx (talk) 10:24, 15 January 2015 (UTC)


 * Jssprojects - The earth's tilt causes the subsolar point to travel between 23.5° north of the equator and 23.5° south of the equator. So it does indeed pass through the center of the sun at those two times per year — once heading north, and once heading south.
 * AstroLynx - Maybe I'm wrong, but it seems that the longitude would be defined by the equinox, not the other way around.
 * --Lasunncty (talk) 08:22, 16 January 2015 (UTC)

Confusion regarding singular/multiple date/times for equinox
The article states "Times of sunset and sunrise vary with an observer's location (longitude and latitude), so the dates when day and night are closest together in length depend on location". Yet in the table to the right of this text, a single specific date and time for "earth's equinox" is given for each year. This apppears to conflict with the information just cited. Is clarification needed?

94.222.0.203 (talk) 05:32, 11 March 2015 (UTC)


 * It's because that sentence is talking about the equilux, not the equinox. This is stated in the previous sentence.  --Lasunncty (talk) 09:27, 18 March 2015 (UTC)

No article on en on Spring Equinox
This is causing havock on cy-wiki, as our Spring Equinox and our Autumn Equinox articles are linked to one English article 'Wheel of the Year'! Llywelyn2000 (talk) 06:41, 21 March 2015 (UTC)

Proposed merge with Chunfen
same topic. see On the History and Actuality of the English Translation for Chinese Twenty-four Solar Terms in Dictionaries Shizhao (talk) 13:46, 19 May 2015 (UTC)
 * oppose see Talk:Winter_solstice. Jimp 06:49, 20 May 2015 (UTC)
 * oppose Also Equinox is not an appropriate page to merge with Chunfen, but March equinox may be so, provided Chunfen refers to the equinox instant rather than the time interval in which the sun moves from the equinox by 15 degrees. Karl (talk) 12:00, 20 May 2015 (UTC)
 * I've read Chunfen and it refers to a period of time not just the instant of the equinox and so March equinox (or Spring equinox) is a poor translation of Chunfen into English a better translation would be Chinese solar term beginning at the March equinox or March equinox solar term. However even this may be a dubious translation, because solar term refers to a point in time and not a period of time. Karl (talk) 12:14, 20 May 2015 (UTC)

Reasons to delete the "Earth-lighting-equinox" diagram
This figure is misleading for the following reasons:


 * 1) It does not correctly show the angle of Earth Axis from the ecliptic. The correct relationship is shown in the "north season.jpg" (Diagram of the Earth's seasons).
 * 2) The wording reads like that the North and South pole tilt toward or away from the Sun. This is not true. The fact is that they do not move much, and they just appear to be tilting toward or away from the Sun because of the Earth movement around the Sun.  — Preceding unsigned comment added by Bitcalc (talk • contribs) 01:15, 26 May 2015 (UTC)

exact time
The article says 2015 autumn equinox will be at UT 8:20. But the referenced source says 8:21, and various other sources say x:22. Why the discrepancy/variation? Is this event not one precise instant for the whole Earth? What is the true exact time, to at least the second? What is the most reliable source?-96.233.20.34 (talk) 14:41, 21 September 2015 (UTC)

over-agressive auto-archiving
It is bad that talk page sections of this article about a timeless long term matter are being agressively auto-archived.-96.233.20.34 (talk) 14:31, 21 September 2015 (UTC)

The most recent few sections should never be auto-archived, regardless of how old they are.-96.233.20.34 (talk) 14:43, 21 September 2015 (UTC)

97?
In discussing the determination of the date of the equinox, observes that "the leap year intervals in [Pope Gregory's] calendar were not smooth (400 is not an exact multiple of 97)", but does not explain the significance of these numbers. The Gregorian leap-year cycle is 400 years long and contains 97 leap years (every fourth year, but not in century years xx00 unless xx is a multiple of 4). Needs clear explanation, which the foregoing is not very. --Thnidu (talk) 08:29, 22 September 2015 (UTC)

2015 sep Equinox: 2015-Sep-23 08:20:33.876
It is very difficult to find the exact times of solstices and equinoxes, to better than a minute of resolution -- and therefore hard to resolve discrepancies in various sources.


 * stellafane.org/misc/equinox.html
 * This source has a handy any-year calculator that gives
 * TDT = Wed, 23 Sep 2015 08:21:33 GMT
 * UTC = Wed, 23 Sep 2015 08:20:06 GMT
 * but the footnotes explain that these times are only approximate, to about a minute of accuracy (and the following shows them to be about a half-min off).


 * www.survival.org.au/solstice2013.php
 * This is the best discussion of how hard it is to obtain exact times, and how to get them from an online NASA calculator:


 * ssd.jpl.nasa.gov/horizons.cgi

Using that engine yields: Ephemeris Type [change] : 	OBSERVER Target Body [change] : 	Sun [Sol] [10] Observer Location [change] : 	Geocentric [500] Time Span [change] : 	Start=2015-09-23 08:20:30, Stop=2015-09-23 08:20:40, Intervals=20 Table Settings [change] : 	QUANTITIES=30,31 Display/Output [change] : 	default (formatted HTML) 2015-Sep-23 08:20:33.000       68.182392 179.9999901   0.0002366 2015-Sep-23 08:20:33.500       68.182392 179.9999957   0.0002366 2015-Sep-23 08:20:34.000       68.182392 180.0000014   0.0002366 2015-Sep-23 08:20:34.500       68.182392 180.0000071   0.0002366 Date__(UT)__HR:MN:SC.fff           CT-UT    ObsEcLon    ObsEcLat

Which leads to: 2015-Sep-23 08:20:32.876       68.182392 179.9999887   0.0002366 2015-Sep-23 08:20:33.876       68.182392 180.0000000   0.0002366 2015-Sep-23 08:20:34.876       68.182392 180.0000113   0.0002366 The dynamical Coordinate Time scale is used internally. It is equivalent to the current IAU definition of "TDB".

Giving a final result of:
 * 2015-Sep-23 08:20:33.876 UTC (+68.182392 = CT/TDB)

In conclusion, 8:20:34 and 8:21 UTC is the proper rounded time, 8:20 is understandable -- but 8:22 seems somewhat wrong, for any general usage.-96.233.20.34 (talk) 21:49, 21 September 2015 (UTC)


 * The Horizons output indicates UT; it does not say if that is UT1 or UTC. According to the US Naval Observatory the prediction is that UT1-UTC = 0.24414 second on 23 Sept. Can you indicate where it is stated whether Horizons considers UT to mean UT1 or UTC? Jc3s5h (talk) 15:47, 22 September 2015 (UTC)


 * I was able to answer my own question. According to HORIZONS User Manual
 * UT
 * is Universal Time This can mean one of two non-uniform time-scales based on the rotation of the Earth. For this program, prior to 1962, UT means UT1. After 1962, UT means UTC or "Coordinated Universal Time". Future UTC leap-seconds are not known yet, so the closest known leap-second correction is used over future time-spans.
 * Jc3s5h (talk) 15:53, 22 September 2015 (UTC)

Lede too detailed
I've read it like 10 times and I still don't understand what the equinox is. Outedexits (talk) 21:01, 2 November 2015 (UTC)

I will simplify it Outedexits (talk) 22:30, 2 November 2015 (UTC)

more precise Solstice and Equinox times
The English speaking world seems to be limited to approximate Solstice and Equinox times, to about the nearest minute. The French offer a more precise, to the second, master table:

2013 	20 	11:01:55 	21 	05:03:57 	22 	20:44:08 	21 	17:11:00 2014 	20 	16:57:05 	21 	10:51:14 	23 	02:29:05 	21 	23:03:01 2015 	20 	22:45:09 	21 	16:37:55 	23 	08:20:33 	22 	04:47:57 2016 	20 	04:30:11 	20 	22:34:11 	22 	14:21:07 	21 	10:44:10 2017 	20 	10:28:38 	21 	04:24:09 	22 	20:01:48 	21 	16:27:57 2018 	20 	16:15:27 	21 	10:07:18 	23 	01:54:05 	21 	22:22:44 Références :  mars • juin • sept. • déc. Institut de mécanique céleste et de calcul des éphémérides
 * fr.wikipedia.org/wiki/Mod%C3%A8le:Solstice-%C3%A9quinoxe

Most WP readers do not care about this -- but some might like access to the more accurate times. How can we provide such access in a good way? Would we ever want to replace our template master table with a more-precise master table of times? -71.174.188.32 (talk) 19:11, 22 December 2015 (UTC)


 * Any of the various language versions of Wikipedia, including this English one, are not reliable sources. If you want to give times to the second, you will have to provide a reliable source for the information. Any template will have to be based on a reliable source, so that any reader with access to the source can verify it. See WP:NOR. Jc3s5h (talk) 20:33, 22 December 2015 (UTC)

I suspect that the source "Institut de mécanique céleste et de calcul des éphémérides" is reliable -- just inconvenient, obscure, and hard for us non-French to understand/evaluate!-71.174.188.32 (talk) 20:56, 22 December 2015 (UTC)


 * I see that fr:Modèle:Solstice-équinoxe contains references to four PDF files, one each for March, June, September, and December. The files are on the website of L'institut de mécanique céleste et de calcul des éphémérides, which I agree is reliable. Whoever adapts the French template to the English Wikipedia would be responsible for reading the PDF newsletters and checking that the template agrees with the newsletters. Or, if the editor doesn't want to create a template, the information could be copied into the article without using a template.


 * I see one error in the template in the French Wikipedia. The newsletters say the times are UT, but the template says the times are UTC. The table covers several centuries before UTC was established. UT is a more generic name, that can mean any variety of mean solar time at Greenwich. I'm sure the folks at L'institut de mécanique céleste et de calcul des éphémérides chose "UT" quite deliberately and it reduces the credibility of Wikipedia to change it to UTC. Jc3s5h (talk) 22:25, 22 December 2015 (UTC)


 * The nasa.gov online astronomy calculator uses UT as a generic term meaning UT1 or UTC depending on context:
 * 'This can mean one of two non-uniform time-scales based on the rotation of the Earth. For this program, prior to 1962, UT means UT1. After 1962, UT means UTC or "Coordinated Universal Time".'
 * If the French source uses a similar nomenclature structuring, than it would be fair to relabel post-2000 times as UTC -- seems to me (i think u understand this topic better than i)... It does seem like we want almost all times mentioned in WP articles intended for general readers to be some flavor of UT.
 * ((note the apparent bug in the display of the unformatted (leading space) lines at the top of this subsection -- i am seeing in Win7/Firefox a spacing glitch on the first 2013 line, that I could not clean up))-71.174.188.32 (talk) 03:42, 23 December 2015 (UTC)

terms
I have copied the following text here from my talk page, for fuller discussion, with the goal of consensus. Lithopsian (talk) 12:58, 3 April 2017 (UTC)
 * In the southern hemisphere do they really call the equinox in March "vernal" or "spring" and the one in September "autumnal" or "fall" in spite of the actual seasons? Also, what leads you to believe the Latin names are more common and less ambiguous than the English ones?  --Lasunncty (talk) 05:43, 3 April 2017 (UTC)


 * See also current discussion at Talk:March equinox. Lithopsian (talk) 12:58, 3 April 2017 (UTC)
 * Vernal equinox is and always has been the name of the "northward" equinox. The name does derive from "spring", but that doesn't mean that it occurs in September in the southern hemisphere, which seems to have become a popular urban myth recently. In circles where equinoxes are discussed on more than two days a year, such as meteorology and astronomy, Vernal equinox is unambiguously and almost universally the term used for the "northward equinox". It has become common in lay circles, in line with the condescension of Latin-phobia that popular media practice, for it to be referred to as the spring equinox. This term appears approximately as common as Vernal equinox in non-technical usage. The obvious consequence is that it clearly isn't the spring equinox in the southern hemisphere, hence March equinox. March equinox is very much the least common term, so on that basis alone March equinox needs to be renamed or removed. In all this, autumnal equinox plays very much second fiddle. The latin-derived proper name is also unfortunately close to English and many people assume that "autumnal" is simply an adjectivised form of "autumn". Lithopsian (talk) 13:41, 5 April 2017 (UTC)


 * I would support merging all the equinox articles to reduce ambiguity and redundancy and to clearly define all the terms used for the two dates. In regards to my original question, it seems there is some disagreement about which terms are used in the southern hemisphere.  But this can be addressed in the article; we don't need to assert that it is always one way and never the other.  And finally, I believe in the case of the equinox, both English and Latin terms are used pretty equally (in contrast to the solstice terms where the Latin names are rare.) --Lasunncty (talk) 01:14, 5 April 2017 (UTC)


 * It would make sense, but I suspect there would be a lot of resistance. March Equinox and September Equinox focus heavily on commemorations, most of which ironically don't call it March Equinox, rather than covering the whole subject in detail to complement and expand on Equinox. Lithopsian (talk) 13:41, 5 April 2017 (UTC)

Similar issues apply to Solstice Karl (talk) 11:40, 6 April 2017 (UTC)

Southern hemisphere
We need to edit this article so that it is not Northern hemisphere-centric, as per the comments in the lead. Is there anywhere in the Southern hemisphere that uses the term 'Fall equinox', maybe even as a translation in the local language, or is it always 'Autumnal equinox'? If someone could clarify this point I'll do the edits. Silas Stoat (talk) 19:36, 18 March 2019 (UTC)

Explanation of the oscillation of the date of the equinox
Jc3s5h's observation that "Nobody ever observed the equinoxes as if they were calculated" etc. is irrelevant. Obviously if you observe the equinox you're not calculating it. Nobody has suggested that anyone ever did this. I'm happy to remove the StackExchange cite as the other one is adequate. 81.139.160.225 (talk) 18:00, 22 March 2019 (UTC)


 * The date and time of the equinoxes and solstices are often obtained from the Astronomical Almanac for the year in question. Those who need an authoritative source before the relevant almanac is published can consult the website of the United States Naval Observatory or Her Majesty's Nautical Almanac Office, who lead the team who prepare the almanacs, and are listed on the title page.


 * The procedure for calculating the equinoxes and solstices are specified on the Explanatory Supplement to the Astronomical Almanac 3rd ed. edited by Sean E. Urban and P. Kenneth Seidelmann. (Mill Valley CA: University Science Books, 2013).


 * From "12.2.1.1 Equinoxes and Solstices" p. 506

"The times of the equinoxes and solstices are defined to be when the Sun's apparent ecliptic longitude &lambda;S is a multiple of 90°; i.e., it is calculated from f(t) = 0 where f(t) = &lambda;S - 0°, 90°, 180°, or 270°."


 * The calculation procedure given on page 508–9 agrees with this definition.


 * The passage inserted by was placed in the lead of the article, which is intended as an overview of the topic. A diversion into some alternate calculation used in an almanac from a Maine farmer's almanac has no place in the article, and especially not in the lead. Jc3s5h (talk) 18:30, 22 March 2019 (UTC)


 * In the original edition of this article Karl Palmen stated that the "equinox occurs on March 19, 20 or 21."  Are you saying that Karl's observation that the equinox might fall on 19 March was wrongly "placed in the lead of the article, which is intended as an overview of the topic"?   If you are not saying that, why are you objecting to the readers being informed that an equinox can happen as late as the 23rd or 24th of the month, as indeed happens with the autumnal equinox at the present time? 81.139.160.225 (talk) 17:35, 23 March 2019 (UTC)

In these edits substantially restored '225's previous edits, which I had removed due to errors, unsuitability for the lead, and, and poor sources. I will now show the numerous problems with this passage in detail.

The added passage is "The dates are variable, dependent as they are on (1) the leap year cycle and (2) the longitude of the perihelion. In 1939 the dynamical mean sun crossed the equator at 10:11 AM (GMT) on 23 March."

The first sentence claims the dates are variable because of the leap year cycle and the longitude of the perihelion. While the variability due to the leap year cycle is described in numerous reliable sources, the dependence on the longitude of perihelion is cited to a popular article from 1930. On the page cited, 579, there is no discussion of the variability of the date of the equinoxes, or is that the topic of the article. Thus no reliable source has been provided to verify that the longitude of the perihelion is the second-most-important cause of variability in the date of the equinoxes.

The second sentence gives the date the dynamical mean Sun crossed the equator in March 1939. But the equinox occurs at the time the apparent celestial longitude of the Sun is 0° or 180°. The date and time the fictitious mean Sun, a.k.a. dynamical mean Sun (formerly used in the calculation of mean time) crosses the equator is not generally of interest in astronomy and will not be found in reliable sources such as the US Naval Observatory website nor in the Astronomical Almanac. The source is a Sky and Telescope about the meaning of the phrase "blue moon". That article dredges through obscure sources to try to figure out where the phrase came from, and is not relevant to the topic of this article. Jc3s5h (talk) 17:32, 24 March 2019 (UTC)

I have added a subsection, "Modern dates", which describes the variability and provides a citation to a reliable source, the Explanatory Supplement to the Almanac 3rd ed. I believe this is more appropriate than adding material to the already-long lead. Jc3s5h (talk) 17:53, 24 March 2019 (UTC)


 * This is most unsatisfactory, since the source quoted is not publicly available.  However, doing the best I can, the mean sun formerly used in the calculation of mean time has nothing whatsoever to do with calculating the equinox.   It circles the equator, while the dynamical mean sun circles the ecliptic.   Since Jc3s5h does not understand this crucial difference he has said that the date of the equinox varies "slightly", when it actually varies by 2d 5h + 1d 22h + 1d 22h, which adds up to a whopping 6d 01h.   So the current version of the article is wrong. 81.139.163.204 (talk) 12:12, 27 March 2019 (UTC)


 * The date and time that 81.139.163.204 represents as the 1939 March equinox, 23 Th 10h 11m eve., is taken from a copy of part of a page from the 1939 Maine Farmer's Almanac which appears in an article in Sky and Telescope by Olsen et al. They write, in the box containing the Maine Farmer's Almanac that "These tables appeared in the 1939 Maine Farmers' Almanac and show that the beginnings of the seasons were fixed by the 'R.A.M.S.' (right ascension of the mean Sun)." Outside the box, in the main text of the article, a few lines later, the Olsen et al. write "Today we usually mark the beginning of the seasons when the Sun's celestial longitude passes 0° (spring), 90° (summer), 180° (autumn), and 270° (winter)."  So your own source agrees with this Wikipedia article was written before your changes. Jc3s5h (talk) 12:56, 27 March 2019 (UTC)
 * You appear to have a competence problem if you can't work out the difference between the start of equal seasons which the writers expressly state are NOT the beginning of seasons as they are generally understood and equinox and solstice times as provided by, for example, the Royal Greenwich Observatory. 81.139.163.204 (talk) 13:24, 27 March 2019 (UTC)

The date and time of the spring equinox for 1939 which IP 81... has repeatedly tried to insert in the introduction has little to do with the actual spring equinox of that year. According to the USNO website the spring equinox of 1939 was nearly two days earlier, on 21 March at 12:28 UT.

That there are other ways of defining an equinox is fine but that can be explained elsewhere and does not belong in the introduction. AstroLynx (talk) 15:43, 28 March 2019 (UTC)


 * I can see two objections to my change.  The first, from Jc3s5h, claims that I represent 23 March 1939 to be the date of the equinox.   Diff, please.   AstroLynx has repeated that allegation.   Again, a diff is needed.   The third point is that the date is included in the lead.   The only reason for that is that Jc3s5h's false claim that "The dates are slightly variable", with accompanying dates, is there.   A swing of more than six days is about 1/50 of a year, which is by no means slight. 81.139.163.204 (talk) 17:42, 28 March 2019 (UTC)


 * In a 400-year cycle, the biggest difference between equinoxes is only about 2.3 days. Where do you get "more than six"?  --Lasunncty (talk) 23:32, 28 March 2019 (UTC)


 * The relevant sentence is here:

There are two components, the leap year cycle, which contributes a variation of about 53 hours, and the angular distance between the equinox and the perihelion, which contributes a variation of about 1 day 22 hours either side of the time when the dynamic mean sun crosses the equinox (in 1939 at 10:11 AM (GMT) on 23 March). For comparison, the true sun, travelling faster than its average speed, passed through the equinox at 12:28 PM on 21 March.


 * Can the anonymous editor please do the math? Name two dates between 1600 AD and the present where the equinox is 5 or more days apart.  The burden of proof for (what appears to me to be) an absurd assertion is on the person making the assertion. LaurentianShield (talk) 01:06, 30 March 2019 (UTC)


 * Here is a link that finds the equinox for any year between 1700 and 2100. LaurentianShield (talk) 01:32, 30 March 2019 (UTC)

The article continues:

The second component is a slow-period variation - the perihelion advances only an average of 6.87° relative to the equinox in the full 400-year leap year cycle.

Example: In 1503 the equinox fell at 09:41 on 14 September (that's 24 September in new money) and in 1696 at 15:04 on 19 March, so there is your "five or more days apart" already. The spacing for 1903-2096 will be found in the article under "Modern dates". Looking at the complete zodiac, in 2021 the sun enters Pisces on 18 February at 10:44 and in 2019 it enters Scorpio at 17:19 on 23 October. So that's an even bigger spacing of nearly 5 1/2 days in little more than a year. 81.139.163.204 (talk) 16:18, 30 March 2019 (UTC)


 * When I issued the challenge above, I specified 1600 to the present to avoid Julian-Gregorian confusion. Nevertheless, in equivalent Gregorian dates, in 1503 the "spring" equinox was March 21 20:43 UTC, and the "fall" equinox was September 24 09:41 UTC.  In 1696, the "spring" equinox was March 19 15:04 UTC, and the "fall" equinox was September 22 03:08 UTC.   I used this site.   I added 10 days to the Julian calendar dates to arrive at (what I believe) are the Gregorian equivalents.  LaurentianShield (talk) 20:01, 30 March 2019 (UTC)

Incorrect perspective for "File:Earth-lighting-equinox_EN.png"
The files in Solstice show the axis tilt lighting correctly alone with the perspective of someone on the orbital plane or ecliptic. The ones here should match the perspective as to not confuse viewers. The perspective with Earth-lighting-equinox_EN shows the lighting above the equator and the sun at a right angle (not the same as the orbital plane). Can someone please correct. John W. Nicholson (talk) 21:03, 27 March 2019 (UTC)


 * All are from the perspective of the equator, so I don't think they need to be changed. Lasunncty (talk) 02:22, 3 April 2019 (UTC)
 * No, review my statements above and think about what you are seeing. Both https://en.wikipedia.org/wiki/Solstice#/media/File:Earth-lighting-summer-solstice_EN.png and https://en.wikipedia.org/wiki/Solstice#/media/File:Earth-lighting-winter-solstice_EN.png show the equator tilted which means these two images are of the perspective of the ecliptic. Watch this: https://en.wikipedia.org/wiki/Ecliptic#/media/File:Ecliptic_vs_equator_small.gif :and think about it; it shows the changes in respect to the ecliptic. However, this perspective is at right angles to the solstice images and its use of the Earth's terminator. In other words, this view is with the sun in front the viewer. Hear is a diagram which shows the correct start of the seasons https://en.wikipedia.org/wiki/Equinox#/media/File:North_season.jpg. (Note: https://en.wikipedia.org/wiki/Equinox#/media/File:South_season.jpg is incorrect because the spin arrows are pointing the wrong way.) John W. Nicholson (talk) 02:32, 4 April 2019 (UTC)


 * Yes, the equator is tilted in those views, but the observer is still directly above the equator. At those points the equator and ecliptic cross, so the view is the same.  (Also, the South_season file you mentioned is correct, but I agree it is a little disorienting.)  --Lasunncty (talk) 22:01, 4 April 2019 (UTC)
 * The this set if photos has your matching equatorial view note the difference: https://en.wikipedia.org/wiki/Terminator_(solar)#/media/File:Seasonearth.png John W. Nicholson (talk) 01:34, 5 April 2019 (UTC)


 * The only difference is the rotation of the image, not the perspective of the observer. --Lasunncty (talk) 21:27, 7 April 2019 (UTC)

Intro

 * This section concern this edit:

As I (sorry for bad wording) the first source doesn't have a single word about plane. It talks about sun itself rather than the plane. I would appreciate much and remove template immediately if you provide me with an quotation proving otherwise. Thanks.  DAVRONOV A.A. ✉ ⚑ 15:16, 9 July 2019 (UTC)
 * The Naval Observatory website seems to be down. While we're waiting for them to fix it, why did you remove the information about related articles at the top of the article? Jc3s5h (talk) 15:59, 9 July 2019 (UTC)
 * If we assume the quote you provided is not taken out of context, the statement by the Naval Observatory "the geometric center of the Sun's disk crosses the equator" is equivalent to the statement in the article "An equinox is commonly regarded as the instant of time when the plane (extended indefinitely in all directions) of Earth's equator passes through the center of the Sun." The Naval Observatory cannot possibly be referring to the Sun's equator because the Sun's center is always in the plane of the Sun's equator, whether it's the time of the equinox or not. The Naval Observatory cannot possibly mean the Sun has somehow moved to the surface of the Earth and passes through the equator, because the Earth would be destroyed. So the Naval Observatory must be referring to the plane of the Earth's equator. Jc3s5h (talk) 16:05, 9 July 2019 (UTC)
 * AFAIK it's blocked for non-US residents, so it isn't down.
 * why did you remove [...] It was a mistake. Sorry for that. I've fixed it already.
 * [...] the quote you provided is not taken out of context [...] There is an archive version. You can checkout it by yourself.
 * [...] the Naval Observatory must be referring to the plane of the Earth's equator I will remove the verification template. Cheers.  DAVRONOV A.A.  ✉ ⚑ 16:39, 9 July 2019 (UTC)


 * I am a US resident. I cannot reach the site either with my computer or my smart phone. So something is wrong. Jc3s5h (talk) 16:55, 9 July 2019 (UTC)

Semi-protected edit request on 23 September 2019
In the "Equinox on other planets" section, it refers to Mars' most recent and upcoming equinoxes. "Mars's most recent equinox was on 22 May 2018 (northern autumn), and the next will be on 23 March 2019 (northern spring)." Fix to "Mars's most recent equinox was on 23 March 2019 (northern spring), and the next will be on 08 April 2019 (northern autumn)."

Kind regards, Churinai Churinai (talk) 04:16, 23 September 2019 (UTC)
 * Yes check.svg Done It's actually 8 April 2020 according to the source, so I've used that. Thanks, NiciVampireHeart 13:48, 23 September 2019 (UTC)

Date section
The section 'Date' is either irrelevant or incomplete. If it is considered related to the equinox then there are a number of other calendars that are much more related to the equinox than the Julian calendar. Even some are synchronized by the equinox. Therefore, the article needs an amendment in this regard. Ehadavi (talk) 17:42, 21 November 2019 (UTC) 21/11/2019


 * This article concentrates on the astronomical event. Cultural aspects of various calendars are covered at March equinox and September equinox. Please review those articles and report back on whether you think the changes you have in mind should be made in this article, or the other articles. Jc3s5h (talk) 19:36, 21 November 2019 (UTC)

Contour plot mis-labels antarctic and arctic circles
The contour plot says "Anta. c." where it should say "Arct. c." and vice versa. 100.16.69.187 (talk) 07:33, 8 March 2020 (UTC)
 * This is c:File:Hours of daylight vs latitude vs day of year with tropical and polar circles.svg., would you like to comment? -- Red rose64 &#x1f339; (talk) 20:34, 8 March 2020 (UTC)
 * That has already been discussed at commons:File talk:Hours of daylight vs latitude vs day of year with tropical and polar circles.svg and is solved now. ◀ Sebastian 20:48, 10 March 2020 (UTC)

Season-specific equinox redirects
I believe the targets of the redirects, , and should be changed from March equinox to Equinox to avoid Northern Hemisphere bias, since March equinox is the wrong target from the point of view of people in the Southern Hemisphere, and Equinox has a hatnote and lead section that can point readers to a more specific article (March equinox or September equinox). I would have changed the redirects myself, but I noticed when checking the page histories that that some kind of slow multi-year unintentional edit war has been taking place on the first two pages I listed, so it seems that there might not be consensus for this change. The current state of the redirects is inconsistent though, since, , , , , , all point to Equinox instead of one of the specific equinoxes. I would not like to just continue the multi-year series of reversions by making the changes myself without a consensus, so I am starting this discussion on what to do about these redirects.

,, , , having made at least one change to the redirect targeting in the last few years, may be interested in discussing.

I understand that ~90% of the human population lives in the Northern Hemisphere, so Northern Hemisphere bias is probably "correct" for most users of these redirects, but it may direct the remaining users to the opposite of what they intend. So I suggest that all of the season-specific equinox redirects should redirect to Equinox. cathartid - talk 05:42, 3 January 2020 (UTC)


 * I have converted these pages to disambiguation pages. Articles such as March equinox are more relevant to a reader than the broad Equinox so helping them get to that page seems good. I reverted the target change at the time since it pointed incoming links (which were seemingly all about the northern hemisphere) away from the intended target. – Thjarkur (talk) 13:41, 3 January 2020 (UTC)
 * This action seems to have created a lot of links to dab pages (Vernal equinox & Autumn equinox) which need to be disambiguated so that users are taken to the right pages.&mdash; Rod talk 16:40, 4 January 2020 (UTC)
 * I've reverted these changes, with no prejudice to the eventual outcome. However, a lot of cleanup needs to be done first.  It isn't really fair to break everything, leave the scene quietly, and expect someone else to fix it all.  Lithopsian (talk) 14:10, 12 January 2020 (UTC)
 * The move of Autumnal equinox (disambiguation) to Autumn equinox should also be done properly, not via cut'n'paste. For some reason, Vernal equinox (disambiguation) was not touched, leaving two dab pages for the same topic.  This idea seems to need a bit more thought and attention to detail.  Lithopsian (talk) 14:18, 12 January 2020 (UTC)

What a mess. We have the following season-related redirects to Equinox: We have the following season-related redirects to March equinox: We have these season-related redirects to September equinox: We have a disambiguation page at Spring equinox (disambiguation) and Vernal equinox (disambiguation) and Autumnal equinox (disambiguation)
 * Autumn equinox
 * Autumn equinox (disambiguation). I've retargeted this to Autumnal equinox (disambiguation)
 * Autumnal Equinox
 * Autumnal equinox
 * Autumnal point
 * Draft:Autumnal equinox (disambiguation). I've speedied this
 * Fall equinox
 * Fall equinox (disambiguation) I've retargeted this to Autumnal equinox (disambiguation)
 * Fall solstice
 * Invernal equinox
 * Spring meridian
 * Spring solstice
 * Vernal point
 * Draft:Vernal equinox (disambiguation). I've speedied this
 * Spring Equinox
 * Spring equinox
 * Vernal Equinox
 * Vernal equinox
 * Vernal equinoxes
 * Autumn Equinox

So, see the RfC below. Shhhnotsoloud (talk) 09:33, 16 February 2020 (UTC)

RfC on season-specific redirects
Should session-specific redirects (e.g. "Spring Equinox") which are not further disambiguated (e.g. "Autumn equinox (northern hemisphere)):
 * (a) target Equinox, or
 * (b) use a northern hemisphere perspective, so target either March equinox or September equinox, or
 * (c) target a disambiguation page

The details can be worked out: this is a question of principle. Please state a preference for (a), (b) or (c). Shhhnotsoloud (talk) 09:43, 16 February 2020 (UTC). Pinging, , , ,
 * Per WP:RFCNOT, this is a matter for RFD, not RFC. -- Red rose64 &#x1f339; (talk) 11:32, 16 February 2020 (UTC)
 * I appreciate that opinion, but this is not necessarily about individual redirects, it's about a principle that would apply for these and any future redirects. Shhhnotsoloud (talk) 17:24, 22 February 2020 (UTC)


 * (c) I would also retarget Spring equinox (disambiguation) to Vernal equinox (disambiguation). --Lasunncty (talk) 01:52, 19 February 2020 (UTC)
 * Comment. Ive pinged a few editors and put Please see notices at 3x disambiguation pages to stimulate any debate. Shhhnotsoloud (talk) 17:36, 22 February 2020 (UTC)
 * I take it you mean ? It pinged nobody, since it was not a new post. See WP:Echo. -- Red rose64 &#x1f339; (talk) 22:54, 22 February 2020 (UTC)
 * Thanks, I didn't know that. Pinging, , , , . Shhhnotsoloud (talk) 10:10, 23 February 2020 (UTC)


 * (a) My preference is to point them all to a single Equinox article, then have a section clarify the hemisphere perspective. Praemonitus (talk) 18:17, 22 February 2020 (UTC)
 * (c) Being sent to the Equinox article is unexpected and the article contains less relevant information. I thought I had already fixed most of these incoming links but apparently forgot/overlooked enough that this was reverted. – Thjarkur (talk) 10:18, 23 February 2020 (UTC)
 * (a) I always prefer to send people to an article where possible, rather than a page that almost certainly isn't where they want to be (unless many people type something into Wikipedia and want a dab page?). The Equinox article isn't ideal for this, but it does contain a section about the nomenclature and its ambiguities.  I agree that just throwing people in at the top of the article is undesirable and unexpected, also that the Equinox section could be improved to make it clearer why people arrived there.  The various articles used to be largely from a northern hemisphere perspective (which I was happy with from my vantage near the north pole!), but the minority audience (those pesky southerners!) got bolshy and started changing things around and now it is all a bit of a mess.  Lithopsian (talk) 15:14, 23 February 2020 (UTC)
 * This argument has some validity in other cases, but looking at Autumnal equinox (disambiguation), I find the page informative by itself. Notwithstanding the offputting name “disambiguation page”, it's actually possible that it already contains just what the reader wanted. So ... (c). As an experiment – and as a compromise between the arguments for (a) and (c) – I further added a short and simple definition of “equinox” for readers who don't know the term. ◄ Sebastian 18:31, 23 February 2020 (UTC)

I am wondering why Vernal Equinox (disambiguation) is now redirected to Spring Equinox (disambiguation), while Fall Equinox (disambiguation) is redirected to Autumnal Equinox (disambiguation). I would have thought we would want to be consistent in using the English vs Latin names. --Lasunncty (talk) 08:17, 12 May 2020 (UTC)

External Links dead
These two External Links seem to be dead; at least they lead to nothing for me:

"Table of times for Equinoxes, Solstices, Perihelion and Aphelion in 2000–2020". United States Naval Observatory. http://aa.usno.navy.mil/data/docs/EarthSeasons.php

"Table of times of spring Equinox for a thousand years: 1452–2547". http://ns1763.ca/equinox/eqindex.html — Preceding unsigned comment added by 2A02:8070:DAF:EE00:DCD6:E056:C203:DDA3 (talk) 13:50, 2 February 2021 (UTC)
 * The Naval Observatory website is stated to be undergoing renovations and was supposed to be available in the fall of 2020. Jc3s5h (talk) 15:05, 2 February 2021 (UTC)
 * I removed the other one, it looks permanently dead. Lithopsian (talk) 16:31, 2 February 2021 (UTC)

Incorrect to compare dates observed in Rome to proleptic Julian calendar
In this edit Eric Kvaalen replaces a statement that Julius Caesar set the date of the spring equinox to March 25 with arguments about when it occurred astronomically. These arguments are invalid and inapplicable because Julius Caesar would have made decisions on the basis of how the Julian calendar was actually observed in Rome during his lifetime, or if making decisions before the calendar went in to force, how it was planned to be observed. But after his death, the rule he made about leap years was not correctly observed, and the surviving documents are insufficient for historians to determine with certainty the conversion between the observed Julian calendar and the Proleptic Julian calendar]. The latter is used by astronomers when presenting dates before AD 8. See [[Julian calendar for more information. Jc3s5h (talk) 16:33, 27 July 2022 (UTC)


 * Once again you have reverted a whole edit just because of one little thing. Yes, there is some uncertainty about whether the Kalends of January of 709 AUC was really January 1 in the proleptic Julian calendar. It might have been January 2 or December 31 in the proleptic Julian calendar (a difference of one day from January 1). But the way you put it (by reverting) it says unambiguously that Caesar set March 25 as the equinox, with no reference at all, let alone a reliable reference. That would only be true if his calendar in 45 BC was two or three days different from the proleptic Julian calendar, not just one day, as I demonstrated in my footnote with a simple calculation and references for the inputs. So our article is wrong after your reversion. Let's restore my edit but reword that sentence a little bit. Eric Kvaalen (talk) 14:34, 2 August 2022 (UTC)


 * If you read the article you will see the part of your comment that says "with no reference at all, let alone a reliable reference" is not true. There is a reference to page 135 of Blackburn and Holford-Strevens. That source states, in a section devoted to 25 March,
 * "In the Roman calendar as reformed by Caesar this was counted as the vernal equinox, being the normal date in the years following the reform...It was also the date of the equinox in the rules devised by the church at Rome for finding Easter, and in the somewhat different system used by Celtic Christians"


 * When the equinox actually occurred is a separate issue from what date Julius Caesar set as the equinox date.
 * As for when it actually occurred, the gist of your calculations seems to be to find a way to smooth out the year-to-year variations due to leap years and other less important factors. I am not aware of a reliable source that has put forth a method for doing this smoothing. Calculations by a Wikipedia editor are unacceptable original research. You would have to find a reliable source that sets out a generally accepted method for smoothing out the date of the equinox, either in general, or for years near 45 BC. Jc3s5h (talk) 15:18, 2 August 2022 (UTC)


 * I don't see any reference to "Blackburn and Holford-Strevens". And why does your quote say that March 25 was the date in the rules devised by the church at Rome? The Computus uses March 21. Eric Kvaalen (talk) 18:22, 24 August 2022 (UTC)
 * The work by Blackburn and Holford-Strevens is footnote number 11 in the article. Julius Caesar, in conjunction with whoever advised him, set the March Equinox on March 25. That was 45 BC. Among Christians, the computus commemorates the death and resurrection of Jesus, which didn't happen until about 77 years later in about AD 33. A lifetime or more passed before Christians decided to commemorate Easter. The rules for the computus differed between the Church in Rome and the Church in the East until Dionysius Exiguus extended a set of Easter tables that the Church in Rome had received from the Church in Alexandria; the first year in Dionysius's table was 532. Before that, Rome used March 25 while Alexandria used March 21. Dionysius used March 21. The computus of Dionysius, after a few hundred years, was used throughout Christianity until the Gregorian reform of the calendar in 1582. Jc3s5h (talk) 19:35, 24 August 2022 (UTC)