Talk:Antarctic Circle

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A polar projection would be nice. OverMyHead 07:55, 28 February 2007 (UTC)

I suggest "northern solstice" and "southern solstice" or "solstice of Cancer" and "solstice of Capricorn". The only great circle mentioned is the equator; the rest are small circles. -phma

Why are you suggesting these terms when they're not the terms that the circles are known as? -- Zoe

It seems to me that "The other great circles are:" is the part that needs to be changed here, not the circles that are referenced. --Brion VIBBER

will major circles suffice? Lir 17:38 Nov 4, 2002 (UTC)

Lir, see great circle. --Ed Poor

On second thought, the circle of latitude really could be re-written for clarity. If I didn't already know what they were, I would hardly have understood any of them. --Ed Poor

What's wrong with circle of latitude? COuld you explain on that talk page, Ed? -- Tarquin 19:43 Nov 4, 2002 (UTC)

Data that needs added, and verified

There's an apparent error in the Arctic_circle article. This ambiguity needs corrected (whichever article is in error) and the relevant data duplicated to Antarctic_circle.

This line "The main long-term cycle has a period of 41000 years and an amplitude of about 0.68°, or 76 km on the surface." does not jibe with this info "The Earth's axial tilt varies between 21.5° and 24.5° with a 41,000 year periodicity" from Axial_tilt.

That's a 3 degree difference, not .68 degree. If the 3 degree figure is correct, this article needs corrected. It would be nice to add the distance range for the Arctic and Antarctic circles to the Axial tilt article.

Suggested merge with Arctic Circle

Please see Talk:Arctic Circle. Thanks. TerraGreen 00:00, 7 January 2006 (UTC)

Centre of the sun

Please see the discussion at wp:Reference desk/Science#A(nta)rctic_Circle Dbfirs 13:10, 20 October 2018 (UTC)

According to [ https://www.pmel.noaa.gov/arctic-zone/faq.html ], "The Arctic Circle is defined as the latitude above which the sun does not set on the summer solstice, and does not rise on the winter solstice", so I would assume that the antarctic circle has a similar definition. According to Sunrise, "Sunrise is the moment when the upper limb of the Sun appears on the horizon". According to Sunset, "The time of sunset is defined in astronomy as the moment when the upper limb of the Sun disappears below the horizon.".

Is there a citation supporting the "centre of the sun" claim? --Guy Macon (talk) 22:53, 20 October 2018 (UTC)

Burn, Chris. The Polar Night (PDF). The Aurora Research Institute. gives a good explanation. The difference is just under one degree of latitude for visibility of the sun so the NOAA definition is only an approximation. Dbfirs 07:25, 21 October 2018 (UTC)

I think I can see what has happened here. The official definition of the Arctic circle is

The Arctic Circle is defined as the latitude above which the sun does not set on the summer solstice, and does not rise on the winter solstice.

I never heard it defined any other way up to now. The approximate latitude is 66° 34'. It is fairly simple to work it out:

Obliquity of the ecliptic = 23° 26'.

On the solstice the sun is overhead at noon on lat. 23° 26'. It will be on the horizon at noon at lat. 90 - 23° 26' = 66° 34'. The upper limb will still be visible until the centre falls more than 50' below the horizon because the semidiameter is 16' and there is 34' of refraction. By that definition, therefore, the circle should be drawn at 67° 24'.

At the other pole, the sun will be on the horizon at midnight at lat. 90 - 23° 26' = 66° 34' as before. This time, the nearer you are to the equator the lower it gets. On latitude 66° 34' at midnight after allowing for refraction and semi diameter the upper limb is at an elevation of 50'. It will therefore just skim the horizon at latitude 65° 44'. The problem with the latest edits is that they do not make it clear that they are talking about the geometric altitude, not the apparent altitude. They are equating "zenith distance 90°" with "being on the horizon", which is an elementary error that, unfortunately, too many people make. 92.23.53.182 (talk) 14:11, 21 October 2018 (UTC)

The arctic and antarctic circles are defined geometrically at approximately 66° 34' as you state. That is the astronomical definition, to match the topics of Cancer and Capricorn. The "folk definition" of the upper limb of the sun on the horizon is a good approximation, but it happens at around 67° 24' as you also state and as observations confirm, though there is variation with atmospheric conditions. I agree that we need to clarify the articles to state that it is the geometric centre of the sun, not the centre of the refracted image on the horizon. I've added a note, but if you can make it clearer, please do so. Dbfirs 15:07, 21 October 2018 (UTC)

Totally unrelated to the Antarctic Circle
The following discussion has been closed. Please do not modify it.
@Dbfirs: Please transfer to your user talk page and delete from here: Sorry I don't have email and your talkpage is protected, so ... You maybe missed my request for a protected edit to Miscellaneous desk on my old user talk page 92.23.53.164. Baseball Bugs is always hatting questions as "trolling" when they're not, and without going to the talk page for consensus, which he is supposed to do. Here's the content of the protected edit request again: This is a serious question (not trolling). I don’t think you’re right about the husband/wife thing. A woman in a lesbian relationship referred to her partner as my husband. In a same-sex relationship does not one partner play the role of the man (husband) and the other that of the woman (wife) in a conventional marriage? See [1]. If you’re wrong about this couldn’t you be wrong about the Camilla/Charles thing as well? On the subject of legal wonkery, see [2]. The county court said the bakers were guilty of discrimination, and so did the Northern Ireland Court of Appeal, but the Supreme Court said they were not. During those four years people may have said "Amy and Daniel McArthur are guilty of discrimination no matter what legal wonkery you can come up with" but they have been proved wrong. Can you cite a judgment (of any court) which says Camilla and Charles are married? — Preceding unsigned comment added by 92.23.53.164 (talk) 11:56, 20 October 2018 (UTC) In this case the law is not even ambiguous. As of 31 December 1949 nobody suggested that Camilla and Charles (had they been of full age and not two years old) could have lawfully married in a register office. Prior to 1837, members of the royal family could only marry in Anglican churches. Under the 1836 Marriage Act they could still only marry in Anglican churches. S.24 made the position clear: And be it Enacted that this Act shall extend only to England, and shall not extend to the Marriage of any of the Royal Family. As of 1 January 1950 the position was exactly the same - s.24 was bolstered by the Marriage Act 1949, s.79(5) which reads "Nothing in this Act shall affect any law or custom relating to the marriage of members of the Royal Family." Just to remove any lingering doubt, in October 1955 Viscount Kilmuir, the Lord Chancellor, confirmed: Marriages of members of the royal family are still not in the same position as marriages of other persons, for such marriages have always been expressly excluded from the statutes about marriage in England and Wales and marriage abroad and are therefore governed by the common law. This means that in England and Wales, such a marriage can be validly celebrated only by a clergyman of the Church of England. So are you suggesting the law has been changed, and if so what is the title of the relevant Act and when did it come into force? 92.23.53.164 (talk) 12:12, 20 October 2018 (UTC) It's such a pain not being able to help querents on the Reference desk, and Soft skin has served notice that he's not going to stop (in fact he's started up again as I write): If you want this to stop delete the LTA page and I promise I will never edit ever again! Sorry, I don't know what all that was about. Dbfirs 16:02, 21 October 2018 (UTC) @Dbfirs: I can't post to the Miscellaneous desk (section "In a same-sex marriage, who is the husband and who is the wife") because Soft skin has been at it and it's protected I can't make a protected edit request to Talk:Reference desk because Soft skin has been at it and it's protected I can't contact you on your talk page because Soft skin has been at it and it's protected I can't contact you on your user page because the system doesn't allow it. Can you add the green text to the section on the Miscellaneous desk? 92.23.53.182 (talk) 16:15, 21 October 2018 (UTC)