Talk:Equinox

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Discussion

Which of the following is a better sentence?

"A zebra is a zoological term for when an animal has a long neck."

"In zoology, a zebra is an animal with a long neck."

The former sentence is how this article and the ones on vernal equinox and autumnal equinox were written. 98.67.160.211 (talk)

Improving an article is good, but there is no need for unfriendly remarks. Patrick 21:48 Nov 2, 2002 (UTC)

I am one of those people who believes in calling a black pot "black". 98.67.160.211 (talk) 14:30, 30 March 2011 (UTC)

Mathematical calculation

"The time at which the sun passes through each equinox point can be calculated precisely—so the equinox is actually a particular moment, rather than a whole day."

I was wondering, how accurate the equinox can be found out. Certainly the mathematically exact moment can not be calculated. The sea quake in the Indian ocean 2004 tilted earths axis by several centimeters so with enough wobbling or vibrations there might even be multiple spring/autumn equinoxes per year. So, is the calculated precision of equinoxes a matter of seconds, ms, us, ns?

There is a difference between the "rotation axis" of the earth and the geographical location where this axis intersects the surface. Because of conservation of angular momentum, the rotation axis cannot be changed by events on earth and so the celestial equator is fixed in space and equinoxes can be determined very accurately (sorry to admit I do not know the current margins). The wobbling mentioned is the movement of the earth's crust relative to the rotation axis and has no bearing on the time of equinox. −Woodstone 12:04, 2005 Mar 28 (UTC)

You are correct that the rotation axis itself cannot be changed by events on earth. However, the 2004 Indian Ocean earthquake article also mentions that "theoretical models suggest the earthquake shortened the length of a day by 2.68 microseconds", which throws off most time calculations by nearly 1 millisecond/year.

It would be nice if this article mentioned the actual formula for calculating the equinox. (If it's too ugly and scary-looking, maybe add a link to some other web page with the actual formula). Alas, my quick Google turns up many pages that mention the book "Astronomical Algorithms" by Jean Meeus, but don't give the actual formula.

You are wrong. Seismic events on Earth can of course change the gravitational cross-section of Earth, and therefore the way and rate of gravitational influence of other bodies upon Earth. The conservation of angular momentum is not a conservation of instantaneous momentum. On average the momentum would remain the same, but in any given short interval it may become irregular. See for example nutation. --70.131.82.146 (talk) 18:47, 2 February 2009 (UTC)

Factual accuracy questions

This article makes two claims which contradict others on the 'pedia. I am uncertain of exactly which is right/wrong, but I suspect this one is:

1. Article claims that at equinoxes day/night are equal. Vernal equinox article says that is not true, and that day/night equal day occurs a few days before or after equinox (This is called the equailux and has been added).
2. Article claims that at poles sun passes from six month day to six month night & vice versa. Other articles (Midnight sun, Polar night) imply the period at the poles is not quite six months day/six months night, but slightly less.

Also, article should explain what a sidereal equinox is, and how it differs from a normal one. --137.111.7.212 10:27, 9 September 2005 (UTC)

It is not a question of right or wrong. It depends on the definition of day versus night.

• Simple definition:
  • day is the period that the true position of the middle of the sun is above the horizon
  • the day and night are equal at the equinox
  • polar night and day are half a year each
• More common definition:
  • day is the period that some direct light of the sun reaches the ground in absense of local obstacles
  • this definition makes the day longer by some 7 minutes or more (width of solar disk plus atmospheric refration)
  • equal day and night occurs a few days before the vernal equinox and a few days after the autumnal equinox
  • polar day is much longer than polar night (and very long twilight)

I will add a short explanation in the text and remove the banner.−Woodstone 20:31:58, 2005-09-09 (UTC)

• Also, the picture in the introduction is kind of flat, anyone have a real satalite photo they'd like to share?--Hello'from^'SPACE 23:48, 14 November 2005 (UTC)

This is all too confusing for me. I quit. ([::]) band-aid 75.121.134.108 (talk) 03:26, 6 May 2009 (UTC)

Merge with Equinoctial point

In response to the suggestion that the entry for 'Equinox' be merged with the entry for 'Equinoctial Point', I favour the retention of the term 'Equinox'. The purpose of an encyclopaedia is to provide access to information to people who may know little about a topic. Otherwise why are they looking it up? Equinox is a term more likely to be used in such cases. The term 'Equinoctial point' can be covered within that entry and in its own entry if more detail is required. P J Lock 130.220.79.98 00:17, 28 September 2005 (UTC).

I have merged Equinoctial point into this article, as per listing in Category:Articles to be merged. Brisvegas 03:10, 10 October 2005 (UTC)

Perhaps as a result of merging, the article does not sufficiently describe Vernal and Autumnal. It discusses them; but: when does Vernal equinox occur? When does Autumnal? This information is not disclosed in the article. Gekritzl 00:49, 6 April 2007 (UTC)

As a result of the merging, someone searching for vernal point, perhaps going from celestial coordinates pages, lands on this page and, IMHO, has a hard time finding the connection. I added in the Names section explicit reference to vernal point. Rlupsa 16:37, 2 October 2007 (UTC)

fixed--Hello'from^{'SPACE 00:27, 15 November 2005 (UTC)}

Help with confusion

I am confused when reading this article because it says on the equinox, day and night are of equal length, 12 hrs each. But from the Sunrise and Sunset times given in my World Almanac, it seems this occurs a few days before the equinox. I was hoping for some kind of simple explanation for why this is so. Thanks ፈቃደ (ውይይት) 22:52, 28 December 2005 (UTC)

Never mind, I see now that the article does give it, I just wasn't reading carefully enough... ፈቃደ (ውይይት) 22:54, 28 December 2005 (UTC)

You can find slightly more information in the article day. −Woodstone 22:57, 28 December 2005 (UTC)

Thanks, I added to that article the Damascus Document's definition of when the Sabbath begins: "No one is to do any work on Friday from the moment that the sun's disk stands distant from the horizon by the length of its own diameter... What I am wondering now is, if one were to define "night" as beginning at that time, and "day" as beginning when the sun was a corresponding distance from sunrise, it would make the day a bit shorter than the night, instead of longer, right? So by that definition, would there be an equinox, and would it occur a few days after the accepted equinox instead of before, and how could it be calculated? ፈቃደ (ውይይት) 23:42, 28 December 2005 (UTC)

Interesting observation. If the sun's disk stands its own diameter from the horizon, that would make the center 16'+32'=48' above the horizon. Subtracting the atmospheric lift of 34', the true position of the sun would be 14'. So indeed the day by this definition would be shorter than the night. The effect is opposite and about 1/3 of the size compared to the modern definition.

Your edit in the article is incorrect. Equinox is defined by the astronomical position of the sun, not the daylight observed. The deviation in time because of the elliptic orbit of the Earth is only about +/- 15 minutes.

−Woodstone 10:44, 29 December 2005 (UTC)

The elliptic orbit seems to mean the Earth is getting more sunlight on one hemisphere for six months even though it's passing farther away, simply because it's tilted toward the Sun during that time, so just facing the Sun does more to affect the seasons than actual distance from it. ፈቃደ (ውይይት) 13:41, 29 December 2005 (UTC)

That is ver true. The amount of sunlight is affected by the tilt of the axis.

Strange as it mayseem the Northern Hemispere is farthest away from the sun when it in the summer season. ( [::] ) 75.121.134.108 (talk) 03:32, 6 May 2009 (UTC)

Lead section

The lead section does not summarize the entire process of an equinox. There is no mention of what dates the equinoxes occur, and it does not explain how long the daytime and nighttime last. (Twelve hours would be a fair hypothesis, but when you look into it, a true equinox divides approximately eleven hours and fifty-some minutes between both the day and night.) The graph does not properly display equinoxes and should be replaced; perchance I will create one myself. Any suggestions concerning my comments? Eternal Equinox 19:44, 28 January 2006 (UTC)

I am going to copy-edit the article since some of my edits were reverted. –Eternal Equinox 21:03, 31 January 2006 (UTC)

The last few edits have created quite a lot of redundancy in the article. The ecliptic/equator and length of day/night issues are both explained three times. Major clean up will be needed. −Woodstone 09:35, 1 February 2006 (UTC)

Agreed, I'll get around to doing that whenever I have the time. Could one please explain this edit? The way I look at it is that once we reach the year 2050, there will be fifty years placed in the article. Is this really necessary? —Eternal Equinox | talk 23:17, 1 February 2006 (UTC)

There was still a lot of reduncancy after the recent clean up. I have now moved the full discussion of "equal night" into the lead section. The more detailed astronomical description and equinoctial point is drawn together with (almost?) complete elimination of redundancies.

I see no harm in having a table with precise date and time for e few years back and quite some years ahead as long as it does not pass beyond the regular text of the article. −Woodstone 14:35, 4 February 2006 (UTC)

IMHO, the following far-better explains what an equinox is  :

"Every year, around March 20th (occasionally the 21st) and then six months later around September 23rd (occasionally the 22nd), our planet reaches a position relative to the Sun wherein, if it had no atmosphere and was perfectly spherical, its north and south poles would be simultaneously poised on the plane of the Earth's terminator (the globe's boundary line between night and day). These two moments on our calendar are referred-to as equinoxes." (added to the main article 8/31/06 by earrach)

Of course, considering those IF's, I suppose we wouldn't be having this conversation, eh? Regardless, I think the above idealized definition is a highly instructive "seed-point" for the discussion and would suggest you consider trying it on your students. Please, ANYTHING other than that utterly despicable "...when the sun crosses the celestial equator." -line used virtually everywhere else. Ugh, ugh, ugh. It "explains" n o t h i n g. earrach

The standard explanation is used because it is indeed used everywhere else. The fundamental and most easily understood definition of an equinox is already in the opening paragraph, that days and nights are equal. That can easily be the opening definition. Your proposed paragraph does not follow Wikipedia style which requires that the title of the article to be the subject of the first sentence, that is, that the title of the article be defined before any explanations are given. I do not regard the positions of the north and south poles relative to the terminator as being particulary instructive for the equinox. It does not belong at the head of the article. — Joe Kress 07:48, 1 September 2006 (UTC)

I am considering your other points but your statement about the day and night being equal as the fundamental descriptor, although being the derivation of the word "equinox" -is- technically inaccurate and has in point already caused quite a lot of discussion here and I fear will continually keep this article's content in dispute without my help. Due to our atmosphere, the globe as a whole always has more day than night because the lit "half" of the globe is always more than half: the sunset and sunrise both "over-wrap" the ideal terminator due to refraction - - a fact that I have embedded in my suggested revision for a "standard" definition. This pushes the local "equal-night" dates off, subjectively/calendrically, relative to the official date which is determined from when the Earth, due to its orbit and tilt, reaches orientation implied in my preferred definition. Unfortunately for purposes of clarity, the only way of being both accurate and concise regarding the "equal-nights" would be to be intentionally fuzzy: "The days around the equinoxes have approximately equal days and nights." - and we know how wikipedians deal with fuzzyness. 9/6/06 earrach

Spring/Autumn ?

The March equinox is only in the Spring in the Northern Hemisphere. Down in the South, it's in the middle of the Autumn. Furthermore, Spring doesn't start on the equinox - it starts halfway between the solstice and the equinox. The equinox would be mid-spring or mid-autumn. 2006-03-02 16:42:17 Vhata

Where exactly in this article do you see the North-centricity? I cannot find it. I see it explaining both ways. Whether spring starts at the equinox or halfway from the solstice is a matter of local culture. Again, where precisely in this article is it biased? For a more extensive comparison, see season. −Woodstone 19:33, 2 March 2006 (UTC)

I was going to make the same remark as the original poster here. There does seem a bit of 'North-centricity' in the table with dates & times at the beginning of the article. By stating 'March (spring starts)' or 'September (Autumn starts)' or however it's exactly put up (don't have firefox at work, can't open tabs!), it's showing a northern-hemisphere bias. It seems like these references connecting specific equinoxes with seasons should either be removed, or prefaced with 'in the northern/southern hemisphere...' 140.142.226.76 19:37, 7 March 2006 (UTC)

You were both right, I overlooked the table. It has been corrected now. −Woodstone 20:21, 7 March 2006 (UTC)

There is also the point that only the temperate climates (between polar circles and tropics) have 4 seasons. In the tropics there are only 2, wet and dryShniken 04:21, 15 March 2007 (UTC)

The term "season" used without qualifiers in a calendrical discussion will always cause dispute and confusion. This is why it may be best to defer to the terms "seasonal quarters" or simply "quarters" (of Earth's orbit / the year...) rather than to whip-up the old annual weather patterns vs astronomical quarters debates. Sept 11th2007 earrach

There is a distinct lack of historical perspecive in the above (!). Listen up: when the Spring Equinox and the Autumnal Equinox were defined, they were defined by the Ancient Egyptians, Ancient Greeks, Ancient Babylonians, and Ancient Romans. There were NO civilizations in the Southern Hemisphere then. Furthemore, 3/4 (75%) of the land surface of the Earth is in the Northern Hemisphere. Yes, only 20% of the Southern Hemisphere is land, but 60% of the Northern Hemisphere is land. Note that ALL of Eurasia and ALL of North America are in the Northern Hemisphere, as well as all of Central America, the majority of Africa and a large portion of South America. These are GREAT reasons why most of the population of the Earth is in the Northern Hemisphere, and why it always will be. 98.67.160.211 (talk) 14:26, 30 March 2011 (UTC)

Image

The image that shows the rays of the sun hitting the earth is perhaps a bit inaccurate. The north pole of the earth should probably be tilted 23.5 degrees toward or away from the viewer (ie, we should be able to see either the north or south pole), since most people will assume that the image is perpendicular to the earth's orbit. 68.6.85.167 01:11, 5 May 2006 (UTC)

The image they've used is actually correct but virtually useless due to the orientation of the view. The image I have always used (see my original rendering below) sidesteps this problem and IMHO, illustrates the -reason- for the equinox pictorially like no other diagram does...

Image:SolcEqx_2006.jpg

...I thought I was the only one who ever thought to "look-down" on the whole pattern for clarification it but did find find one a bit similar but not really the same up in the corner of a page in Guy Ottwell's good old "Astronomical Companion". Now THERE is a great illustrator of astronomical ideas!

Earrach 22:46, 21 June 2006 (UTC)

Your image cannot be used on Wikipedia because it is copyrighted. — Joe Kress 00:47, 2 October 2007 (UTC)

You should be clear that this is from a NORTHERN hemispheric perspective. Arthurian Legend 04:35, 21 March 2007 (UTC)

Eric's image is much better than the ones on the Wikipedia page. A famous study of how people understand (or misunderstand) the solar system, including interviews with random students at Harvard, and other research shows that the "perspective view" of the solar system that shows the orbit as an ellipse is one of the main causes of confusion. Most folks see this and interpret it as the earth is at times closer to the sun, and thus this is summer (they just don't get that when the N hemisphere has summer, the S hemisphere has winter). While I think Eric's image may need improvement (I think it's still a little unclear what's going on in it), I believe it is important to move away from images that show elliptical orbits.

For a bit of my own background and why I might know this, I have taught high school science (mostly physical) for fifteen years, and spent one year writing curriculum for a program at Lawrence Hall of Science where we spent much time reviewing research into scientific misunderstandings. Lee 18:09, 24 June 2007 (UTC)

I agree that this image is much better than any currently in the article. I do have one suggestion: Turn the season names around so that they are read in the correct order (counterclockwise). --Lasunncty 03:44, 25 June 2007 (UTC)

recently found on wikicommons Sidelight12 (talk) 05:56, 29 July 2012 (UTC)

Aurora Borealis

What are the effects the Equinox has on the Aurora Borealis? 71.112.224.112

- Aurora Borealis is caused when fast charged particles of the solar wind hit the outer atmosphere of Earth. As such, the relative position of Earth and Sun to one another (on the date of Equinox or anytime else) should have no effect on Aurora Borealis - these are two independent phenomena. --Hyugens 10:41, 5 October 2007 (UTC)

Equilux

This should be added back in to the article. Here is a source http://www.tribuneindia.com/2008/20080321/science.htm#2. This talks briefly about it. If you need others I can give you a few textbooks which state the meaning. —Preceding unsigned comment added by 204.58.248.32 (talk) 19:34, 10 March 2009 (UTC)

Statment moved from article:

• Although the word "equinox" implies equal length of day and night, as is noted elsewhere, this simply isn't true. But for most locations on earth, there are two distinct identifiable days a year where the length of day and night are the closest to being equal. Those days are commonly referred to as the "equiluxes" to distinguish them from the equinox. The equinox is a point in time, but the equiluxes are days. By convention, the equiluxes are the days where sunrise and sunset are closest to being exactly 12 hours apart. This way, you can refer to a single date as being the equilux, when, in reality, it spans sunset on one day to sunset the next, or sunrise on one to sunrise the next. As an example, for a city 45 degrees N and 123 degrees W (Portland, OR), the 2006 autumnal equilux is on Sept 25 when sunrise is at 7:01 am and sunset is at 7:02 pm. The 2006 autumnal equinox is on Sept 22 at 9:03 pm. Note that for the Northern Hemisphere, the autumnal equilux lags behind the equinox, and the reverse is true in the spring. As you might suspect, the whole situation is also reversed for the Southern Hemisphere.

I cannot find any substantial support for the name "equilux" on Google. Please provide a good citation for its "common" use and for its "conventional" meaning. If not, then reword without "equilux". — Joe Kress 07:01, 24 August 2006 (UTC)

From google:

http://groups.google.com/group/sci.astro/browse_frm/thread/95431b5b56640874/d6ae5b193523fbfa?lnk=st&q=equilux&rnum=3&hl=en#d6ae5b193523fbfa

The term equilux is discussed and used by both professional and amateur astronomers from organizations as diverse as the Lick Observatory and Swedish Amateur Astonomer Federation (SAAF) going back at least 12 years. OK to move statement back?

Wiredknight 22:32, 24 August 2006 (UTC)

Maybe equilux its own article? (with a link from equinox) --Tauʻolunga 23:33, 24 August 2006 (UTC)

Thanks for the citation. If the paragraph is moved back, the ref must be included. I do remember a rather detailed discussion in another article on a related subject that mentioned the semi-diameter and refraction of the Sun. I'm not sure whether it discussed earliest sunset/latest sunrise (near winter solstice) or something akin to 'equilux'. So it is discussed elsewhere on Wikipedia in some form, which may or may not be more appropriate. — Joe Kress 04:37, 26 August 2006 (UTC)

It's described in for example in the wiki article day. −Woodstone 12:33, 26 August 2006 (UTC)

The article I was thinking of was equation of time, which was actually discussing something related but different, the shift of sunrise/sunset times caused by tilt and eccentricity. However, this shift does not change the relative amount of daylight and nighttime. — Joe Kress 05:03, 27 August 2006 (UTC)

When are the days equal?

The sentence "The real equality of day and night happens a few days towards the winter side of each equinox." appears to be incorrect because as written the winter side is dependent on which hemisphere you are in. Readers in different hemispheres would assume opposite meanings. Personally I do not know the correct solution, but I would like to read what it is. --Roger Bays 05:11, 19 March 2007 (UTC)

Well, the correct solution is, "In the Northern Hemisphere, the real equality happens before the March equinox and after the September one. In the Southern Hemisphere, after the March one and before the September one." So the sentence is not uncorrect, but probably a bit ambiguious. I agree that readers may be confused. Rija 14:40, 19 March 2007 (UTC)

Indeed it seems that the formulation in the article is a bit sloppy in suggesting that the day and night can be equally long at the equator. On the equator precisely, looking at only the true position of the Sun (midpoint, no atmospheric lifting) the time between successive passings of the horizon is always 12 hours. So still at a position on the equator, but now taking into account the diameter of the apparent Sun's disk and the atmospheric lifting, the day is always longer than the night. Only at positions far enough from the equator to eliminate these effects by a shortening day (and equal lengthening of the night), the day can be equally long as the night. These positions are always located in a well defined hemisphere, so the concept of winter is well defined. −Woodstone 19:34, 19 March 2007 (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

What does this have to do with the actual Equinox?

Okay seriously... Solar terms in East Asia

Main articles: Chunfen and Qiufen

The traditional East Asian calendars divide a year into 24 solar terms (節氣). Chūnfēn (pīnyīn) or Shunbun (rōmaji) (Chinese and Japanese: 春分; Korean: 춘분; Vietnamese: Xuân phân; literally: "vernal equinox") is the 4th solar term. It begins when the Sun reaches the celestial longitude of 0° and ends when it reaches the longitude of 15°. It more often refers in particular to the day when the Sun is exactly at the celestial longitude of 0°. In the Gregorian calendar, it usually begins around March 20 and ends around April 4 (April 5 East Asia time). Qiūfēn (pīnyīn) or Shūbun (rōmaji) (Chinese and Japanese: 秋分; Korean: 추분; Vietnamese: Thu phân; literally: "autumnal equinox") is the 16th solar term. It begins when the Sun reaches the celestial longitude of 180° and ends when it reaches the longitude of 195°. It more often refers in particular to the day when the Sun is exactly at the celestial longitude of 180°. In the Gregorian calendar, it usually begins around September 23 and ends around October 8. The Chinese character 分 means division, so the vernal equinox and the autumnal equinox signify the middle of spring and autumn, respectively, unlike in Western cultures.

This should be in the SEE ALSO section and its own article or in an later paragraph, not the initial paragraph about its name in English. Did the words Chungen and Qiufen have any influence on the word aequus nox? No? Then it doens't belong in this section. IT DEFINITELY does not belong in the beginning of this article as it doesn't explain what an equinox is and it is not relevant to the definition or the important of equinoxes in the English speaking/Western world. —The preceding unsigned comment was added by Arthurian Legend (talk • contribs) 04:42, 21 March 2007 (UTC).

That section was moved from near the end of the article to its present position near its beginning (with some modification) by Yao Ziyuan on 25 November 2006. Obviously, he didn't want it near the end of the article. However, I agree that in this English version it doesn't belong near the beginning because interrupts the explanation via an excursion. — Joe Kress 20:42, 21 March 2007 (UTC)

Terminology: Coordinate system vs Reference frame

minor nit

I suggest distinguishing between Coordinate System and Reference Frame. The former is a description of the quantities used to describe a reference frame e.g. the Cartesian Coordinate System, the Spherical Coordinate System. Reference Frame refers to Coordinate Systems in practice, or an Instance of a Coordinate System if you will, though a single Reference Frame may of course be described using more than one Coordinate System. bcarcich@astro.cornell.edu 24.59.125.201 19:12, 9 April 2007 (UTC)

Formal defintion of Equinox times

The US Naval Observatory and Her Majesty's Nautical Almanac Office both use a very precise definition of the equinox (and solstice) times. It is the time at which the apparent ecliptic longitude of the Sun is 0° or 180° (90 or 270 for the solstices). See http://asa.usno.navy.mil/SecM/Glossary.html This definition has no direct link to the seasons, but nevertheless it the one used by the USNO and HMNAO to calculate the equinox times. As authorities on the matters astronomical, their values are the ones published in newspapers around the world, and mentioned on TV.

ExtonGuy 03:10, 4 September 2007 (UTC) ExtonGuy

As the ecliptic longitude is defined in relation with the vernal point and the vernal point is one of the intersection points of the ecliptic and the celestial equator, the above is equivalent to the definition in the article. However, it would be worth noting it in the article. -Rlupsa 07:03, 26 October 2007 (UTC)

There's a nice table of equinoctes in the article, complete with time. However, which time zone is shown? UTC? EDT?--Pgranzeau (talk) 16:20, 18 March 2008 (UTC)

As the first word in the top line says: it's UTC, the only fitting choice for a document with international readership. −Woodstone (talk) 20:58, 18 March 2008 (UTC)

Amount of discussion/focus on equal day/night

For a particular latitude (not the equator), an equal day and night can occur at no more than one spot at that latitude on the Earth’s surface per equinox. This would be true even if the Earth's orbit was circular, the Sun was a point light source, and there was no refraction of light. The tilt and orbit of the Earth are all that is required to insure the above result.

Given that an equal day and night is rare, I wonder if the amounts of discussion/focus on the phenomena which affect the equality of day and night are needed. Possibly, these phenomena could be grouped together in a section with the discussion of “equiluxes”. There are several comments which imply that widespread equality of day and night can be achieved on the day of the equinox if these phenomena are ignored. I do not believe this to be the case. Irrespective its Latin roots, the connection of equinox with more than an approximate equality of day and night appears to be problematic.

An instructive connection can be made between equinox and orbital elements and geometry. By considering the Sun to be in an apparent tilted orbit around the Earth (with the equatorial plane as the reference), the ascending node of the Sun’s “orbit” can be seen to correspond to the northern vernal equinox and assigned a longitude (along the reference plane) of zero. The descending node of the Sun’s “orbit”, which is in line with the ascending node (two planes intersect in a line), corresponds to the northern autumnal equinox and has a longitude of 180 degrees, etc. Like northward and southward equinoxes, ascending and descending (nodes) equinoxes are not dependent on one’s hemisphere. A benefit of discussing orbital elements and geometry is that a strong relationship between the equinoxes and the solstices can be developed.

AikBkj 06:31, 23 September 2007 (UTC)

I disagree. The title of this article is equinox, hence its most important characteristic, equality of day and night, should be prominently discussed, regardless of its rarity. Orbital characteristics are already discussed in the article. You can improve that discussion. — Joe Kress 19:38, 25 September 2007 (UTC)

The fact that the name implies equality of day and night is my major concern. This implication is incorrect in that an equinox is a moment in time and not an extended period of time. Additionally, this popular notion does not match the actual technical meaning of equinox. Equinox is a misnomer (A misnomer is a term which suggests an interpretation known not to be true, also, ...a difference between popular and technical meanings of a term.). So, should the article bow to and help to propagate the popular misinterpretation and misunderstanding of equinox or should it try to clarify the more accurate meaning of equinox? I think that a large amount of discussion and focus on the phenomena which affect the equality of day and night does the former. AikBkj 02:41, 26 September 2007 (UTC)

We should recognise that there are several meanings: the precise astronomical instant and the date on which by "some" definition day and night are close to equal. Explanation of the difference merits attention. −Woodstone 10:01, 26 September 2007 (UTC)

Agreed, I can see your points, a triumph of practicality over technicality. But in another couple hundred years when the technical definition has become the most popular usage, ... AikBkj 15:43, 26 September 2007 (UTC)

Tides

Why was there no mention of the flood tides caused by the equinoxes?

I took a quick look at the wikis on Tide and Flood. I was not able to find any connections between them and equinoxes. The phrase "spring tide" is commonly used, but, "spring" used in that case was not a reference to the season. AikBkj 18:25, 11 October 2007 (UTC)

There is very much a connection between the tides and the equinoxes. The British Marine Life Study Society states that "the highest spring tides of the year occur after the equinoxes in March and September, and these tides are often the best time to visit the shore."

When I lived in Washington (state), I knew that the best time to visit the beach was during the equinox, because the pull on the tides is much greater; during one equinox the tide is much higher than normal (this is most likely the "flood tide" mentioned above), and during the other it is extremely low, and you can walk hundreds of feet out on ground that is normally underwater, and find all kinds of little critters that you don't see closer to the shore, like chitons. My mom and I visited the beach every year at that time. I am surprised that Wikipedia doesn't mention this fact. 75.208.228.90 (talk) 15:51, 15 April 2008 (UTC)

The equnoxes have absolutely nothing to do with the tides, and if you have seen some such association, that was purely concidential. The highest high tides and the lowest low tides occur when all of these events coincide, which is not annually and is not particularly often:

A. Either the full moon or the new moon occurs when the Moon is at its perigee in its elliptical orbit around the Earth.

B. The Earth is at its perihelion in its elliptical orbit around the Sun, and this occurs in January of each year.

Hence, the highest of high tides an the lowest of low tides always occur in January, which is about as far from the equinoxes as is possible. This is because the winter solstice occurs in the latter part of December each year.

98.67.160.211 (talk) 14:12, 30 March 2011 (UTC)

Re trivia, facts and fables

I'm a new user (W7632416, Brian, San Diego).

I have taken the new-user tutorial. I do not recall seeing a detailed policy concerning trivia, but I see that trivia sections are discouraged. (I happen to agree.)

I think I see how editing works in general and how this discussion page is the vehicle. So let me try my hand at this.

How do we feel about the appropriateness of the first entry under "Trivia, Facts and Fables" section?<br />

"Ancient people with astronomical knowledge knew that the Vernal Equinox shifts into the next Zodiac sign (constellation) every 2150 years, and the passing of every age was celebrated. it is said that the birth of Moses is the biblical translation for the end of the age of the worship of Taurus the bull (false idols) into Aries, and the birth of Jesus is the translation of the shift from Aries to Pisces-the fish. Researchers state that the three kings and the star above Jesus's birthplace were the Three Kings Stars from Orion's belt that align with the star Sirius when the december 25 Equinox shifts into Pisces. Thus Jesus represents the sun, and his most important dates are the Christmas equinox and the Easter equinox. Some people even say that Jesus was created as a earthly person when the holy Roman Bible was written in 300AD in their translation of the Astrological Scriptures."

I recognize the content as part of the documentary film Zeitgeist II, but that's not the point. I think the paragraph should be removed for being unverifiable. Or out of place, or something. My Wiki experience level is too low for me to simply delete the passage even though I think a consensus to do so will occur (arise?).

I hope it's appropriate to invite comments about this, my first attempt at initiating an edit, to my user page, I think it's called. (Talk page?) Thanks for bearing with me.
--W7632416 03:00, 26 October 2007 (UTC)

Paragraph removed. Btw, this is not your user page, which would be User:W7632416. This page is the article's discussion page, and you used it appropriately. And welcome ;) --Gulliveig 03:16, 26 October 2007 (UTC)

Atmospheric effect

The 100 arcminutes of extra daylight makes the day about 7 minutes longer than 12 hours. Similarly, the night is about 7 minutes shorter than 12 hours. So, (12 hours + 7 minutes) - (12 hours - 7 minutes) gives a difference between day and night of about 14 minutes as the article stated. AikBkj (talk) 17:19, 8 January 2008 (UTC)

Some sections of this article must be placed in an external article

"Heliocentric view of the seasons" and "Geocentric view of the seasons" must be placed in an external article. The reason is both sections are in Solstice and Equinox articles, and corrections in one are not synchronized with the other. —Preceding unsigned comment added by Cablop (talk • contribs) 14:12, 16 February 2008 (UTC)

Cultural aspects

The section has a part beginning : "The Christian churches calculate Easter as the first Sunday after the first full moon on or after the March equinox.". That is not so.

The Easter dates given by the British Calendar Act are based on March 21st; the Equinox is I think not mentioned. The date of the true Equinox depends on one's longitude. The moon used is not the actual one, but a defined approximation. Since the Catholic rule gives the same Easter dates, it must correspond.

Perhaps : "The Christian churches calculate Easter as the first Sunday after the first nominal full moon on or after March 21st.".

In this part of the article, one must discriminate carefully between the instant of the true astronomical equinox and the calendar date chosen to represent it.

82.163.24.100 (talk) 12:05, 7 June 2008 (UTC)

You ignored the next sentence: "The official definition for the equinox is on 21 March." Although the date of the astronomical equinox does depend on your time zone and hence your longitude, this addendum fixes it on 21 March. Although you are correct that the British Calendar Act of 1750 does not mention the equinox, the original 1582 Catholic papal bull Inter gravissimas does explicitly mention both the equinox and 21 March: "the vernal equinox, which was fixed by the fathers of the [first] Nicene Council at XII calends April [March 21]" (English translation). You are also correct regarding the "full moon", so "Paschal" should be prefixed to it. Hence some slight rewording is warranted. As a sidebar, both the Protestant portions of the Holy Roman Empire as well as Denmark, Norway, and Sweden used both the astronomical full moon and the astronomical equinox at Uraniborg via Kepler's Rudolphine Tables to calculate Easter from 1700 until either 1775 or 1844, depending on the country. — Joe Kress (talk) 19:54, 7 June 2008 (UTC)

Inaccurate bulleted items in Cultural aspects section

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)

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)

Time concerns

Forgive me if there's a precedent, but as this site is international shouldn't time be in GMT? GMT is, after all, the basis for world time. Concerned reader, first time talker. 92.20.127.246 (talk) 11:21, 22 September 2008 (UTC)

The table at the head of the article gives times in UTC, which is the atomic form of GMT. UTC, not GMT, is the basis of most world times. UTC is even the official basis of time within the United Kingdom, but they call it GMT. — Joe Kress (talk) 21:06, 25 September 2008 (UTC)

Lead

The equinox is essentially an event. It happens at a certain time and location. Definition: the Sun passes the equator (as viewed from Earth). Location nor time from the actual equinox. The location is then used in the definition of the orbital elements. −Woodstone (talk) 14:22, 25 September 2008 (UTC)

Both location and time are used in astronomy. From The explanatory supplement to the Astronomical Almanac (page 727): "equinox either of two points on the celestial sphere at which the ecliptic intersects the celestial equator; also the time at which the Sun passes through either of these intersection points; …" Note that its location is the primary definition — its time depends on its location. — Joe Kress (talk) 20:56, 25 September 2008 (UTC)

Fully agree that the word equinox is sometimes used to signify either the location or time. But the definition is the event (involving a rotating body orbiting around another). Place and time are secondary. The location is not the definition, it is used in the definition. I think all of this is now correctly stated in the simplified lead. −Woodstone (talk) 22:12, 25 September 2008 (UTC)

I completely disagree. 'Event' is a neologism not used in any definition that I have checked, including standard English language dictionary definitions. All definitions agree that it is either a time or a location, not an 'event'. — Joe Kress (talk) 00:49, 26 September 2008 (UTC)

What the?

I haven't been here for a while and I'm staggered at the current status of the Lead and various other parts of the main article. IMO it looks like somebody dumped sections of a (bad) highschool research paper throughout the main article. Far, far from encyclopedic style; poor construction; repetition and irrelevant and contestable data throughout. Yes I'm speaking in generalities and havent cited the particulars but this is Wiki, so I'll start editing instead. My apologies to whomever. Earrach (talk) 01:28, 30 September 2008 (UTC)

I have pulled/edited...

(1.) the first line of the Lead section which read: "In astronomy, an equinox is each of the events that the Sun passes over the Earth's equator, in its annual cycle. By extension it also signifies the time at which it happens and the apparent position of the Sun at that moment." - as so obtuse as to be inaccurate: so much attention is being paid to "event or not event" that the writer failed to justify in the least what (on earth...) "passes over the equator" might mean.

SO, I inserted in its place my own concoction (follows,); have at it boys! New text: "Equinox is a term from Spherical Astronomy referring to the intersection on the celestial sphere of the celestial equator by the plane of the ecliptic. The term is thereby used as a name for a specific junction on a set of spherical coordinates and also, being that these coordinates derive directly from the rotation of the earth and its inclination on its axis as it orbits the sun, a date for the arrival of the earth-sun system on the annual calendar which causes the aforesaid intersection."

I once again placed this (my text) at the lead because of the return of the ambiguous "event" and "passes over the equator" text: C'mon, the sun "passes over the equator" every day of the year! Do you mean to say the noon sun passes through the zenith when viewed from the equator? The "event" is the geocentric observation of the sun crossing the CELESTIAL Equator... -is that what you wish to cite? I feel my paragraph covers that -and places it in context. 64.58.246.82 (talk) 20:48, 21 October 2008 (UTC)

(2.) cut down considerably on jumbled text of the "Names" section and reordered it to run from commonest to least-common names

(3.) I pulled the following: "There is either an equinox (autumn and spring) or a solstice (summer and winter) on approximately the 21st day of the last month of every quarter of the calendar year. " as unnecessary and contestably wrong as worded.

(4.) I also pulled: "* The spring equinox marks the Wiccan Sabbat of Ostara (or Eostar), while at the autumn equinox the Wiccan Sabbat of Mabon is celebrated." and may replace it with something about the Neopagan observances but calling upon less unnecessary/debatable detail.

Earrach (talk) 02:09, 30 September 2008 (UTC)

Formatting with bullets

This article doesn't have enough bullets. Can we add an extra 15 bullets to each section? I think that will make it much easier to read--Elysianfields (talk) 15:07, 16 January 2009 (UTC)

Ambiguous geometry

At an equinox, the Sun is at one of two opposite points on the celestial sphere where the celestial equator (i.e., declination 0) and ecliptic intersect. These points of intersection are called equinoctial points—the vernal point and the autumnal point. By extension, the term equinox may be used to denote an equinoctial point.

Two infinite planes intersect along an infinite line, not two discrete points. The 'celestial sphere' is a model of uncertain radius, and this explanation neglects parallax. Wherever a person actually observes the celestial sphere from a point on Earth's surface, the sun is not at one of two discrete points. Two observers in different parts of the world will not agree on where these points lie. The stated coordinate system is relative to an imaginary observer at the center of the Earth. Anyone else has to make adjustments. --70.131.82.146 (talk) 18:40, 2 February 2009 (UTC)

PER THE ABOVE: The location of the observer is irrelevant to the definition of an equinox (or solstice). The event is defined by the relationship of the center of the Sun and the center of the earth and the "ideal" plane of the earth's night-day terminator, relative to the inclination and attitude of the Earth's axis. This is the very reason why the "Sun over the equator" and "Sun crossing the celestial equator" are such misleading descriptors and, worst of all, so far from playing any tacit role in explaining the "whys" of what an equinox is. AGAIN, all factors considered, the simplest and most instructive description of an equinox is to say that equinoxes occur twice a year (on either sides of the Sun) only at the moments that the full length of the Earth's axis momentarily lies in a plane perpendicular to a line from the center of the Earth to the center of the Sun. -EARRACH 64.58.246.196 (talk) 20:19, 8 May 2009 (UTC)

The night-day terminator plays no role in the definition of the equinox. Crossing the equator is the essential point. Part of the year the Sun is North of the equator, another part it is South of it. The moment it switches sides is the equinox. It is then neither south nor north—otherwise expressed: it is over the equator. −Woodstone (talk) 20:31, 8 May 2009 (UTC)

The very plane mentioned above(containing the Earth-center point and perpendicular to a line from earth center to sun center) is the plane we commonly associate with the terminator, and, in the moment the full length of the Earth's axis lies in that plane, it is the generator of all the described effects ascribed to the equinox from Spherical Astronomy. Yet, the Spherical Astronomy jargon (crosses Celestial Equator; Ecliptic, etc.)never attempts to describe the cause of those very effects. Scroll-up and compare with the blue illustration above. -Earrach 206.107.152.68 (talk) 21:19, 8 May 2009 (UTC)

Technically true, but a very roundabout way of expressing it. The described line through centres of Earth and Sun crosses the equator at the equinox. No need to hop to the plane perpendicular to that line and then consider the axis relative to it. −Woodstone (talk) 22:43, 8 May 2009 (UTC)

Tecnically equinox

To make it not sound so "Rocket science" equinox actually means that there is an equal length of day and an equal length night. —Preceding unsigned comment added by 98.64.110.184 (talk) 23:45, 21 March 2009 (UTC)

Myths, fables and facts

This section states that " UTC, which is at least four hours in advance of any clock in the Americas". This is incorrect. Argentina (ART) is UTC-3h (and even UTC-2h for DST, but at least last year it was applied only until March 15, not affecting the equinox). Bertou (talk) 14:01, 3 May 2009 (UTC)

 Done Set Sail For The Seven Seas 196° 51' 14" NET 13:07, 23 March 2010 (UTC)

SAD

Is it a stretch to link seasonal affective disorder to this article? I have it and it usually kicks in around the Autumnal equinox, with the shorter nights etc. I was also reading about studies linking SAD to the autumnal equinox itself rather than the obvious shorter days and colder nights. Something about the actual gravitational effects related to the Autumnal equinox. --Piepie (talk) 17:30, 14 October 2009 (UTC)

• Also: druids. --Piepie (talk) 17:37, 14 October 2009 (UTC)

I don't think seasonal affective disorder is related enough to equinoxes, since the equinoxes are at a fixed point in time while seasonal affective disorder tends last beyond the autumnal equinox, though the winter solstice and ending at the vernal equinox. However, the midnight sun and polar night articles link to seasonal affective disorder and have a few words on it as well. Hope this helps.   Set Sail For The Seven Seas  275° 49' 0" NET   18:23, 14 October 2009 (UTC)

Tilt of the earth's axis relative to the plane of its orbit about the sun

The opening sentence (2010-03-02)

"An equinox occurs twice a year, when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, the Sun being vertically above a point on the Equator."

seems to suggest that it is the angle of the earth's axis of rotation (axial tilt) relative to the orbital plane which has changed - when in fact it is not that tiny precession that is meant at all.

The illustration to the right on the page which intends to show the earth with equal light on the hemispheres is presented as if the axis is vertical (no tilt, normal to the orbital plane) confirming this impression - as it is shown as vertical in the illustration.

Can we not obtain a gif rather like that now used for lunar libration?

The WP article at Axial tilt is very clear in comparison.

I have a few suggestions: on VE the sun rises in east for us all and near the north pole finally appears above the horizon at noon. At the equator, the angle of its path incident to the horizon at sunrise and sunset is roughly an indication of the earth's axial tilt. The height of the sun at zenith on VE is about (90 - your latitude). If you look at that altitude on the meridian 6 months later at midnight, you will see that you looking into Pisces near Aquarius at the VE on the celestial sphere.

One place to see hemisphere bias is in images of the moon. For VE, 2 gif's should do it. One reason for concern is that so many web sites are using this kind of wp article for info. —Preceding unsigned comment added by Grshiplett (talk • contribs) 02:31, 4 March 2010 (UTC)

G. Robert Shiplett 23:02, 3 March 2010 (UTC) —Preceding unsigned comment added by Grshiplett (talk • contribs)

This line is not meant to suggest that the axial tilt of the Earth has changed, but that it has no radial inclination with respect to the Sun, since the inclination is perpendicular to the radius of the Earth's orbit and parallel to its circumference. Hope this helps. Set Sail For The Seven Seas 17° 2' 15" NET 01:08, 4 March 2010 (UTC)

Thanks!! That cleared up exactly what I was wondering about. So I hope you don't mind that I have quoted/paraphrased you in the introduction.76.113.104.58 (talk) 02:44, 14 April 2011 (UTC)

Grshiplett has a valid point. However, if the new image continues to show a vertical terminator bisecting daylight and nighttime halves of Earth, then one pole must be in view and the other hidden. This would bias the article toward one hemisphere. — Joe Kress (talk) 01:46, 4 March 2010 (UTC)

I see what you mean. The plane of the ecliptic need to be included somehow in order to clarify things. Set Sail For The Seven Seas 226° 27' 0" NET 15:05, 6 March 2010 (UTC)

Article prose

“ On March 20th, Dutch immigrants to Northwest Iowa commemorate the Vernal Equinox by celebrating El Gato Negro. Traditionally, young men gather in heemstra hall to don themselves in togas and body paint, and proceed to walk around under the cover of night proclaiming that "spring has sprung." They credit the coming of spring to El Gato Negro, a mysterious black cat that smiles favor upon the northern hemisphere by slaying the Great Rat King of winter and chasing his minion ghosts back to the southern hemisphere, thus allowing for the Vernal Equinox to take place.

According to history [1], the Vernal Equinox of 2010 marks the 6014th since the world was created by God on October 23rd, 4004 BC, but only the forth in which a black cat has been randomly credited for the changing of the seasons. El Gato Negro is said to be conceived immaculately in order to regulate seasonal change.
Celebrants claim "his handiwork is a great and terrible mystery. However, I think we've pretty much figured it out: It is a well-established fact by the scientific community that cats are the only mammals capable of seeing ghosts. It is also scientific fact that ghosts lower the temperature of any place where ghosts are present. Finally, it is an unconfirmed rumor that ghosts are terrified of black cats and therefore flee from their presence." Therefore, the weather changes not because the Earth tilts, but because El Gato Negro travels to the northern hemisphere and scares away the cold-causing ghosts.
On the designated night, a celebrant of honor is chosen to carry the Cup of Flame to symbolize the coming warmth, and a town crier is chosen to carry a megaphone. Young men are also encouraged to sleep without clothing until the Autumnal Equinox.

”

@24.116.57.114 - could you verify this? Thanks. Set Sail For The Seven Seas 355° 42' 0" NET 23:42, 8 March 2010 (UTC)

Suggestion

Here is a view that clarifies it for me. However, I am not an authority so the view may be technically wrong. If it is correct then adding it or something similar should clarify "time of equinox".

Imagine a vector from the center of the sun to the center of the earth. Imagine the plane P which passes through the center of the earth and is perpendicular to that vector. As the earth revolves around the sun the plane moves with it. The two equinoxes are the exact two times during the earth's orbit when its axis is entirely in P.

~G. Blaine —Preceding unsigned comment added by G. Blaine (talk • contribs) 01:09, 22 March 2010 (UTC)

That does seem accurate. One could also say that the equinoxes are the moments when the center of the Sun is on the plane of the Earth's equator. I think that is even simpler. CosineKitty (talk) 01:15, 22 March 2010 (UTC)

Uh, yeah... See my images (linked in @ "One Good Picture" two topics down from here,) and discussions above (search this page with term: "earrach"). Your vector and its perpendicular plane (which I refer to as "the plane of the ideal Earth terminator") is simply THE generating factor for both the equinoxes and the solstices. Thereby my-preferred "definition" of and equinox never passes muster with all these geocentrists... (mine runs: "EQUINOX: The Spring or Autumn quarter begins as the plane of the Earth’s terminator, the boundary-line between night and day, simultaneously crosses the North and South Poles. Therefore, with the Earth’s day/night boundary line briefly poised simultaneously on both poles, only on dates near these times of year are the number of hours of night and day equal all over the globe." - Earrach. Earrach (talk) 17:13, 20 March 2013 (UTC)

Confusing sentence

I can't tell what this passage is supposed to mean, and it is ungrammatical on top of that: "Therefore, when specifying celestial coordinates for an object, one has to specify at what time the vernal point (and also the celestial equatorial) are taken. That reference time is also called equinox." The parenthetical remark seems like a mistake, but I'm not sure what it was intended to mean. CosineKitty (talk) 18:09, 22 March 2010 (UTC)

This is due to the fact that the origin of the ecliptic longitude and the origin of the right ascension are based on the March Equinox. Due to the precession of the equinoxes, the tropical year is shorter than the sidereal year and therefore the March Equinox, which is based on the tropical year will appear to move with respect to the celestial sphere, which is based on the sidereal year. Therefore, the origin of the ecliptic longitude and the origin of the right ascension will change over time and the equatorial coordinates are relative to the year of observation. In order to be able to compare coordinates, a common time or epoch will need to be specified. Hope this helps. Set Sail For The Seven Seas 208° 45' 44" NET 13:55, 23 March 2010 (UTC)

I did a poor job explaining what my problem is. I am an experienced amateur astronomer, so I do understand about precession, nutation, etc., and how the intersection of the ecliptic with the celestial equator changes over time. What I am talking about is the parenthetical remark mostly: "and also the celestial equatorial". Reading this again today, my best guess is that it was supposed to say "celestial equator". CosineKitty (talk) 15:08, 23 March 2010 (UTC)

I think I see what you meant now. How about leaving out that section so that it reads,

“ Therefore, when specifying celestial coordinates for an object, one has to specify at what time the vernal point is taken. ”

then it should be a lot clearer and easier to understand. Hope this helps. Set Sail For The Seven Seas 259° 28' 15" NET 17:17, 23 March 2010 (UTC)

Yes, I would tend to agree with you, though there is a separate issue. It looks like this was put in to provide an opportunity for linking to Equinox (celestial coordinates). This brings up a separate issue that I have brought up on its talk page. The claim is that the word equinox is used in a similar sense as Epoch (astronomy), but with an alleged different meaning. I am skeptical about the distinction. The closest I can find is the phrase equinox of date used in a book, but in a way that is synonymous with epoch. That other discussion may have a variety of outcomes, which would affect whether I would want to leave the link to Equinox (celestial coordinates) here or not. CosineKitty (talk) 18:40, 23 March 2010 (UTC)

I see, however you don't need to display the title name to get the link to the page, for example,

“ Therefore, when specifying celestial coordinates for an object, one has to specify at what time the vernal point is taken. ”

or something similar will do the job just as well. Also, if Epoch (astronomy) and Equinox (celestial coordinates) turn out to have the same meaning, then a merge of the 2 pages would probably be of interest. Hope this helps. Set Sail For The Seven Seas 317° 0' 0" NET 21:08, 23 March 2010 (UTC)

One good picture . . .

Even with all the fancy graphics accompanying this article, there is not one picture that clearly illustrates the idea of an equinox. Not one.

How about a simple line drawing of a spherical earth in a position of equinox in its orbit around the sun? And perhaps emphasizing how the axis of the earth is leaning neither toward the sun nor away from it? Would that be so difficult?Daqu (talk) 19:54, 19 September 2010 (UTC)

Go right ahead and make it. As you intimate, that can't be difficult. −Woodstone (talk) 16:42, 20 September 2010 (UTC)

I am replacing the current image, File:Earth-lighting-equinox EN.png, with an image found on Earth's rotation: File:AxialTiltObliquity.png, which shows Earth as viewed from the Sun at the March equinox. Unlike the existing image, the new image includes lines showing Earth's axis and orbit, so Earth has a noticeable tilt relative to its orbit, neither toward nor away from the Sun. Even so, a better image is possible. — Joe Kress (talk) 07:34, 21 September 2010 (UTC)

HERE YOU GO guys, if someone can direct me to how to make these originals of mine Wikipedia-"Copyright-ok", you can use them. This is the way i've been explaining the equinoxes (and solstices) for decades - and have never seen it shown this way anywhere else. You see if you look down on the solar system from above, something that has always seemed obscure and difficult becomes very clear (if you can unlatch yourself from the traditional Spherical Astronomy "Sun crossing the celestial equator" definition.) === LINK (A): https://docs.google.com/open?id=0B6LolKoM98rjb04zQmxmWm9HdEU === LINK (B): https://docs.google.com/open?id=0B6LolKoM98rjYW5MeEVVRDRoRWM ===Earrach (talk) 21:04, 2 October 2012 (UTC)

The length of the summer daytimes in the Far North

"Far north of the Arctic Circle, at Longyearbyen, Svalbard, Norway, there is an additional 15 minutes more daylight every day about the time of the Spring equinox, whereas in Singapore (which is just one degree of latitude north of the Equator), the amount of daylight in each daytime varies by just a few seconds."

---

This statement above appears to be irrelevant as well as inaccurate. That number of "15 minutes" seems to have been drawn out of a hat, too. In Svalbard, the lengths of daylight and nightime at the equinoxes are approximately equal, just as they are at Singapore or nearly anywhere else on the globe (except for quite close to the poles -- perhaps within 500 km).

---

Here are the relevant facts: Daytime in Svalbard becomes very long (24 hours a day) in the month or more around the Summer Solstice. Nighttime in Svalbard becomes very long (24 hours a day) in the month or more around the Winter Solstice. Daytime and nighttime in Singapore are nearly equal in length every day of the year. They are absolutely equal near the times of the two equinoxes. Recall that each of the equinoxes is about 33 hours long. Stating that an equinox occurs on a specific hour, minute, and second is a bunch of baloney. 98.67.160.211 (talk) 15:31, 30 March 2011 (UTC)

Day and night are never "absolutely" equal at points on the Equator, due to refraction.

"each of the equinoxes is about 33 hours long"

Anyone know what his definition of equinox is? Tim Zukas (talk) 20:51, 22 January 2013 (UTC)

Heliacal rising and setting

Without mention of the material found in heliacal rising the idea of the path of the sun against the stars may not make sense to some readers - and does not make sense historically. In the western world, school starts and ends at fixed times and few classrooms of students ever witness a heliacal rising or setting of a star - it is not within their learning experience. Children raised on farms in the American Midwest with open horizons may have noted this when milking cows - city dwelling children are largely denied this exceept for the anecdotal "star bright, first star I see tonight". Asking 12-year-olds at noon to indicate the area on the visible horizon where the sun rose or where it will set can give you an idea of how vague something so fundamental has become. By comparison, horoscope and astrological sign are thriving in the public ken. Children who fish may know the time of "dawn" and "dusk" in summer as those relate to fishing regulations w.r.t. time before sunrise and time after sunset. G. Robert Shiplett 11:46, 6 May 2011 (UTC) —Preceding unsigned comment added by Grshiplett (talk • contribs)

ERROR in CAPTION of TILTED-EARTH GRAPHIC BELOW TABLE of SOLSTICE & EQUINOX DATES!

The caption currently reads: "Illumination of Earth by the Sun at the March equinox." The caption should read instead, "Inclination of Earth to the Ecliptic at December Solstice" as correctly shown in the table accompanying the magnified view of the graphic.

-Charlie Cottingham
Atlanta, GA
Cott4Treks@aol.com — Preceding unsigned comment added by 65.7.147.229 (talk) 12:58, 3 July 2011 (UTC)

No, the caption is correct. Read the labels carefully. I admit it is hard to read unless you click to view it full size. I'm not sure which table you are referring to. --Lasunncty (talk) 10:47, 4 July 2011 (UTC)

Should we expand the image, or edit it for better clarity in its current size? --Lexein (talk) 17:59, 4 July 2011 (UTC)

OTD

Per the rules at WP:OTD, this article is going to be omitted from Wikipedia:Selected anniversaries/September 23 this year because it requires maintenance. I realize that it has been included in years past, but we have been making an effort to tighten up the rules. You'll notice that it was skipped for the March equinox 2011 as well. There are over 6 weeks to go, so hopefully that gives editors enough time to take care of this. Thanks. howcheng {chat} 19:31, 1 August 2011 (UTC)

suggest correction in the article Equinox

Section :Heliocentric view of the seasons

First line: The axis of the Earth is tilted at an angle of about 23.44 degrees from its orbital plane.

Should be: The axis of the Earth is tilted at an angle of about 23.44 degrees from the perpendicular line of its orbital plane. — Preceding unsigned comment added by 134.171.162.136 (talk) 21:36, 16 September 2011 (UTC)

Equinox as an orbital event

In plain language,the Equinox occurs when the North/South poles lie on the circle of illumination as planet turns to the central Sun about a traveling axis that stretches through the center of the Earth from Arctic to Antarctic circles.The Earth has two daylight/darkness cycles,one due to daily rotation and the other cycle being the polar daylight/darkness cycle which is due solely to the orbital behavior of the Earth,the North/south poles act like a window into this orbital behavior of the Earth so as those locations turn to the central Sun with a daylight/darkness period lasting a single year ( roughly 6 months of darkness is followed by 6 months of daylight),the correct line of reasoning should be to drop 'tilt' towards and away from the Sun and look at what is happening with the orbital motion of the Earth.This is a large modification to the work of Copernicus who based seasonal changes on variable axial inclination whereas the contemporary view is to introduce an additional orbital component to act in tandem with daily rotation to explain events such as the Equinox Gkell1 (talk) 19:01, 22 September 2011 (UTC)

Temporary semiprotection to prevent vandalism requested

I request the article to be semiprotected for a few to couple days or so because Google shows a doodle of Spring north of the equator while I think Google shows a doodle of Autumn in the southern hempishere, and the Wikipedia article should be on the top of the listings, making it an easy target for vandalism. ELITE 3000 (talk) 04:09, 20 March 2012 (UTC)

Looks like there's only been one vandal edit since the article became publicized by Google.com, so I doubt any admin would accept a protection request just yet. You can make an official request here: Wikipedia:Requests for protection#Current_requests_for_protection. You may want to wait until we see more vandalism occurring. — FoxCE (talk • contribs) 06:36, 20 March 2012 (UTC)

First Point of Aries and First Point of Libra

In the Names' table, it is stated that those points are based on constellations, while the Wikipedia article Right Ascension states (correctly) that "...the first point of Aries, which is the place in the sky where the Sun crosses the celestial equator at the March equinox", meaning an intersection of the ecliptic with the equator. Shouldn't the table information be corrected?--Macalves (talk) 11:50, 2 May 2012 (UTC)

No, it means the names are constellation-based, not the points themselves. The comment box hints at the definition you provided, but perhaps it could be more clear. --Lasunncty (talk) 01:36, 4 May 2012 (UTC)

Easter Germanic Origins Deceptive

In your article you write: "The Pope was moved by the desire to restore the edicts about the date of Easter of the Council of Nicaea of AD 325. Incidentally, the date of Easter itself is fixed by an approximation of lunar cycles used in the Hebraic calendar, but according to the historian Bede the English name comes from a pagan celebration by the Germanic tribes of the vernal (spring) equinox."

During the time of the Council of Nicaea of AD 325, there were no Germanic celebrations of Easter. The word "Easter" might be of a Germanic origin, however, it has no place in defining the origin of this word in relation to this religious tradition. The word "Easter" is actually a corruption of the ancient name of the Goddess deity Ishtar/Ester, for whom this traditional sacred event was actually absconded by the Roman papal. She was known to the Hebrews as "Ester" and to the Phoenicians/ Canaanites as "Ishtar," and to the Greeks as "Artemis," and to the ancient Egyptians as "Isis." The Catholic papals also knew her as "Ester" having borrowed from the Hebrews. They "Christianized" and "Anglicized" her as the "Black Madonna." Nearly all of the Roman Catholic holy rites, holidays and celebrations, were taken from these much older traditions surrounding this ancient Goddess, especially the tradition of her divine kings.74.229.102.208 (talk) 14:34, 5 May 2012 (UTC)

Suggested improvement to sentence structure.

Change this ...

"This point (the place on the Earth's surface where the center of the Sun can be observed exactly overhead) crosses the Equator moving northward at the March equinox and crosses the Equator moving southward at the September equinox."

To this ...

This point is the place on the Earth's surface where the center of the Sun can be observed exactly overhead as the Sun crosses the Equator moving northward at the March equinox and crosses the Equator moving southward at the September equinox.

Because ...

The point does not cross the equator. — Preceding unsigned comment added by 69.172.86.118 (talk) 23:57, 19 May 2012 (UTC)

It is referring to the subsolar point, which does indeed cross the equator on the equinoxes. --Lasunncty (talk) 09:14, 25 May 2012 (UTC)

File:Seeing Equinoxes and Solstices from Space.ogv Nominated for speedy Deletion

An image used in this article, File:Seeing Equinoxes and Solstices from Space.ogv, has been nominated for speedy deletion at Wikimedia Commons for the following reason: Copyright violations What should I do? Don't panic; deletions can take a little longer at Commons than they do on Wikipedia. This gives you an opportunity to contest the deletion (although please review Commons guidelines before doing so). The best way to contest this form of deletion is by posting on the image talk page. If the image is non-free then you may need to upload it to Wikipedia (Commons does not allow fair use) If the image isn't freely licensed and there is no fair use rationale then it cannot be uploaded or used. If the image has already been deleted you may want to try Commons Undeletion Request To take part in any discussion, or to review a more detailed deletion rationale please visit the relevant image page (File:Seeing Equinoxes and Solstices from Space.ogv) This is Bot placed notification, another user has nominated/tagged the image --CommonsNotificationBot (talk) 09:42, 23 June 2012 (UTC)

Is "equilux" really a word?

It's in barely one or two of the thousands or millions of books searchable by Google Books. Perhaps we should mention that this word is vanishingly rare. 86.159.192.146 (talk) 19:40, 11 August 2012 (UTC)

About "equilux" in the introduction

The last paragraph of the introduction is very misleading. I was trying to find out if equinox is the same date all over the earth, and the last paragraph implied that it isn't; that it depends on your location. However, luckily I read a little deeper, and found that this was for extremely technical reasons, namely that the shape of the sun will make its light reach earth a little earlier than its center rises over the horizon, and that the start of the "day" is defined by this moment, so the "real" equinox is not (necessarily) the same as the astronomical interpretation of it, and it will occur at a little different times depending on your place. As far as I can tell, this is an extremely technical discussion that does not belong in the introduction, and only help to confuse readers. For all intents and purposes, equinox is at the same date and moment at every location on earth, and this needs to be completely clear in the introduction. 210.194.84.251 (talk) 05:52, 6 October 2012 (UTC)

Merge

Per previous discussions at Spring equinox, Fall equinox, Autumn equinox, Autumnal 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)

wikt: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#Equinox and Solstice articles. – Wbm1058 (talk) 20:57, 6 March 2013 (UTC)

Lead requires a simple fix

There's a typo in the footnote that's currently #3. The word Oxford is misspelled (the d is missing). I'd fix but the lead is locked.—PaulTanenbaum (talk) 12:48, 19 February 2013 (UTC)

• Fixed. Note that the page is only semi-protected. HelenOnline (talk) 12:55, 19 February 2013 (UTC)

Merge and Equilux

I see no problem with merging the two occurrences. They are properly called the Spring Equinox and the Autumnal Equinox. Also, I think the term "equilux" needs better explanation. An equilux is a day when sunrise and sunset are closest to 12 hours apart (e.g. the sun rises at 0650 and sets at 1849). An equinox occurs at a specific time while an equilux is a full day. The Spring Equilux is a few days earlier than the Spring Equinox and the Autumnal Equilux is a few days later than the Autumnal Equinox. Yes, equinox literally means equal but that is misleading, it is not that. Dangnad (talk) 23:24, 14 March 2013 (UTC)

Unclear

1.

"An equinox occurs twice a year (around 20 March and 22 September), when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, the center of the Sun being in the same plane as the Earth's equator. The term equinox can also be used in a broader sense, meaning the date when such a passage happens."

I find the distinction between the first sense and the "broader" sense hard to understand. If the point is that "equinox" can mean either the event or the time it happens, then this is probably too nit-picky a distinction to give such prominence to (or bother with at all), but if kept it needs to be explained more carefully in my opinion. At the moment I think the second sentence is more confusing than helpful.

2. It would be better if the opening sentence began with definition in the form "An equinox is..."

3.

"Another meaning of equinox is the date when day and night are the same length.[3] Times of sunset and sunrise vary with an observer's location (longitude and latitude), so these dates likewise depend on location and do not exist for locations close to the Equator. To avoid this ambiguity the term equilux is sometimes used in this sense.[4][note 1]

I find this whole paragraph confusing. Only by special coincidence would any place on Earth have exactly the same length of night and day on the same date. It is also unclear why a date when day and night are the same length should specfically not exist near the Equator, which is the one place where day and night are most equal in length throughout the year. — Preceding unsigned comment added by 86.179.119.114 (talk) 21:00, 28 April 2013 (UTC)