Talk:Apsis

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In architecture, apsis is also the plural of apse

Is that really correct? The original Latin term is apsis, plur. apsides. From apsis derives Eng. apse which can hardly have apsis as plur.

Sebastjan 11 March 2004 10:45 (CET)

Isn't there something slightly odd in the term "furthest approach"? Evercat 01:40, 15 Mar 2004 (UTC)

Contents

[edit] Apogee

There is a link on this page to apogee which simply links back to this page. This page says nothing about the term apogee though.

[edit] Perijove and apojove

Why should "perijove" and "apijove" be avoided? Sez who? They are probably plainer.

Rlquall 19:00, 19 Aug 2004 (UTC)

It is considered very bad form to mix Latin roots with Greek, which is what "perijove" does. Jupiter is Zeus in Greek, and the corresponding Greek root is Zeno, hence perizene/apozene.
Urhixidur 15:41, 2004 Aug 20 (UTC)
"This is the kind of impertinence up with which I shall not put!"--Churchill Seriously, to say it's "very bad form" is extreme pedantry, along the lines of "never split an infinitive". Wikipedia doesn't seem to have a List of words combining Latin and Greek roots, but 'automobile' is the canonical example. Perijove and apojove are far more commonly used than perizene and apozene. NASA uses them; why shouldn't we?
—wwoods 19:37, 4 Oct 2004 (UTC)
If NASA uses them then that should at least deserve a mention in the footnote. Wikipedia should be descriptive rather than prescriptive, IMO; we should use the most widely-used term even if it's "wrong", though its "wrongness" should still be pointed out. Bryan 23:27, 4 Oct 2004 (UTC)
And the "wrongness" is of the "Thou shalt not wear a cloth woven of wool and linen" (Deut. 22:11, I ♥ Wikipedia) variety. The usual terms are better, since someone who hasn't seen them before stands a good chance of understanding -jove = -Jupiter, while nobody is going to make the leap -zene = -Zeno = -Jupiter. Without context, I'd have guessed they were geologic periods.
—wwoods 16:12, 7 Oct 2004 (UTC)

Further to this, I have just toned down the 'it is considered more correct to use the greek form for the body'. It's not specified who considers it correct, and as these are all scientific terms, I think it's best to go with what the scientists actually use, regardless of any linguistic concerns. Otherwise, you might as well put a note in the Television article saying that 'proculvision' or 'teleopsis' are considered more correct. Also, I couldn't find any use in the literature of the '-cytherion' or '-areion' terms, so I moved mention of those from occasionally used to never used. Worldtraveller 08:43, 22 Apr 2005 (UTC)

Absence of evidence is not evidence of absence, as Einstein used to say. The problem with trying to find quotes in the litterature through the Web is that there are still huge gaps. You wouldn't be able to find the first use of -saturnium mentioned in the article because it only exists as scanned-in GIFs on the web (I stumbled across it serendipitously). A lot of the litterature of the mid-20th century has yet to be made available either. The term -cytherion, apparently, was introduced by Carl Sagan in the 1960s...But just try and prove it! Anyway, I think the article is reaching a pretty decent equilibrium point by now.
Urhixidur 17:32, 2005 Apr 22 (UTC)

Indeed, very true, but if we can't cite our sources, then the information is not verifiable, and I think that's very important for an encyclopaedia. I'd say anyway that the gaps in online coverage of astronomy literature are not that huge. The Astrophysics Data System contains scanned versions of a huge number of journals right back to issue 1 in most cases ([1], [2]), and even allows you to search OCR'd text of scanned journal articles [3]. Checking now uncovers a total of 87 refs to -saturnium including the one you chanced across [4], of which 8 are in the last 50 years. Still no sign of perizenes, -hermions or others though. I still question, I'm afraid, the statement that some scholars object to these combined forms. Who are these scholars? If you can show me an example of a scholar actually saying that perijove should not be used, then that is worthy of including, but seeing as perizene is never used, it seems odd to try and give it credence by including it here in the table with perijove. We don't do the same with other hybrid words such as television, although they do have an article about them at hybrid words. I've now commented out the forms which do not appear anywhere in the available searchable astronomical literature. If they are actually used in journal articles anywhere, then they should be included, and sources should be cited, but otherwise they're just neologisms. Worldtraveller 19:18, 22 Apr 2005 (UTC)

[edit] Excellent explanaiton

That would explain with regard to most of the planets, then, the more obscure (to most of us) Greek vs. Latin form, and why "Perilune/Apilune" would be totally incorrect for "Periselene/Apiselene". Excellent.

Rlquall 15:54, 20 Aug 2004 (UTC)

[edit] Aphelion's Pronunciation

It's not clear to me what the proper pronunciation is for "aphelion", from a linguistic point of view. My copy of the American Heritage Dictionary (2nd college edition) gives the options of "a-feel-yon" and "a-feel-e-on". Indeed, almost every (perhaps every) Greek work that's come into English turns the greek letter Φ (phi) into a FFF sound.

However, it is the case that, rather than being a mere hypercorrection, 'ap-helion' would indeed be the ancient pronounciation, if we were able to bring some ancient Greek speaker to this time and show him or her the written word. (Source: Vox Graeca, by Sidney Allen, the standard book on the prounciation of Ancient Greek) I guess I'm uncomfortable hearing it called a Hypercorrection, since it does, in fact, reflect the classical pronunciation, which is being taught increasingly these days to students of Ancient Greek. (When I was studying Ancient Greek twenty-five years ago, the pronounciation we were taught was the Erasman Pronounciation, which pronounces Φ (phi) as FEE. The Modern Greek pronounciation of the letter is also FEE, and that's how I hear it pronounced when I attend a Greek Orthodox church service.)

The comment made in the article -- about "Greek από, from, which becomes απ before a vowel, and αφ before rough breathing)" -- is absolutely true. However, the sound change only makes sense when you understand that the ancient Greeks really did pronounce Φ (phi) as an aspirated P sound, like the P that starts the English word "pin", where we release a puff of air, a sort of soft H, after the P. Try it yourself, then compare with the way you say the P in "stop", where you don't release the puff of air. Again, this change makes sense only if you understand that "apo helion", by the ancient sound transformation rules, naturally turns into ap' helion, which turns into "aphelion". And the only way that change is natural is if it's pronounced in the classical way. So go figure.

Saugart 06:04, 27 August 2006 (UTC)

[edit] Missing Definitions

The article needs to define what mu and 'e' are. I know e is called the eccentricity. I have no idea what mu is. --69.5.156.155 14:11, 14 Dec 2004 (UTC)

"MU" is gravitational parametr for central body, i.e. product of its mass and gravitational constant.

217.11.255.138 3 July 2005 19:06 (UTC) (A.Vitek from CS.wiki)

[edit] earth's apogee/perigee

When are Earth's apogee and perigee? (Presumably, it's at around the same time each year.) I know it's not the same as the solstice, so when are they? --Carl 01:59, 1 Jan 2005 (UTC)

Apogee around July, perigee around January, I think. However, unlike Mars, the Earth's orbit has low eccentricity and thus the distance difference between perigee and apogee is more or less negligible and doesn't affect the weather noticeably. -- Curps 07:46, 1 Jan 2005 (UTC)
Shame on you Curps for not spotting the mistake. Earth has no apogee or perigee because it does not revolve around itself! For Epoch J2000, Earth's perihelion occurred on January 3, 1999, aphelion on July 5, 1999. The following years, perihelion occurred on January 4, 2000, January 3, 2001-2003, January 4, 2004. Aphelion was on July 4, 2000-2001, July 5, 2002-2003, July 4, 2004. Next occurrences are January 3, 2005 and July 5, 2005.
Urhixidur 15:25, 2005 Jan 1 (UTC)

[edit] Pronunciation of aphelion

I'm sure that many books stating that the correct pronunciation of aphelion is ap-helion can be found. However, the Greek word suggest the exact opposite. The classical Greek word for sun is ἥλιος (hēlios). The preceding preposition is ἀπό (apo). When this is prefixed to another word that begins with a vowel it looses its final ο, and if that word begins with the spiritus asper, the π is aspirated into φ. Thus the compound word is ἀφήλιον (aphēlion), not ἀπήλιον (apēlion). If you feel that the ph in photograph, pheromone and physics should be pronounced with an /f/, then the same holds true for aphelion. Gareth Hughes 01:31, 6 Mar 2005 (UTC)

Presumably your typical classical Greek would have a lot more trouble with the meaning of the word than with its pronunciation. :-) How would a modern Greek pronounce it? Anyway, whatever its roots, it's an English word, and not bound by its ancestry.
—wwoods 19:00, 22 Apr 2005 (UTC)
All right, let's start looking at sources. For now I'll put just this one because that's all I've got here. More to follow:
  • Webster's Ninth New Collegiate Dictionary (1989) : afelyon (also attests -cynthion, -gee, -lune; note that -astron and -apsis are absent)
Urhixidur 19:16, 2005 Apr 22 (UTC)
  • The OED concurs with the /af-/ pronunciation; they cite that Kepler coined the term around 1596, and also that there was an alternative form, aphelium, for a time.

Fcw July 4, 2005 00:34 (UTC)


[edit] Redirection from Pericenter

I was redirected to this page from the term 'pericenter', as used in article S2_(star), but the page does not contain the word, let alone the definition. --128.9.216.23 17:36, 17 August 2005 (UTC)

[edit] mnemonics

Are thre any useful mnemonics to help remember which one (peri- or ap-) refers to the closest point and which refers to the far point? I can never remember without checking this page. SigmaEpsilon → ΣΕ 05:14, 9 December 2005 (UTC)

Use the word "away" (as in away from the earth) to remember aphelion. Russ

[edit] Question

I wanted to find out what a perihelion is, but this article is completely incomprehensible. Could there be a friendlier explanation? I dont think it's really that complicated. —The preceding unsigned comment was added by 194.80.49.125 (talk • contribs) 15:43, 9 August 2006.

I'm sorry that you find the article difficult. Please explain what could be done to make it more accessible/relevant. A perihelion is a point in space at which an object (usually in orbit around the sun) is closest to the sun. The Earth's perihelion is the moment when it is closest to the sun. THe furthest point from the sun is called the aphelion. — Gareth Hughes 14:58, 9 August 2006 (UTC)

[edit] The diagram doesn't show any apsis

203.144.143.7 15:19, 4 September 2006 (UTC)Chris

[edit] Perigee but no apogee article

Is there a reason that there is an article for perigee, but not apogee? Perhaps these should all be merged? Or should the apogee article be created? Lunokhod 21:35, 16 January 2007 (UTC)

[edit] Advance of perihelion

Obviously the perihelion of the Earth varies a few days correponding to a few degrees or some thousend seconds of arc every year. That's much more than the relativistic advance of 43“ per century – not year – as predicted by general relativity for the planet Mercury. 84.169.216.201 09:38, 21 March 2007 (UTC)

As clearly seen form the table of data, the advance of perihelion is fluctuating by some days (one day is about 3,600“) from year to year. There is not a continuous advance every year or century. Therefore, it just nonsense to say Earth or Mercury have a certain advance of perihelion per century caused by some effect due to general relativity, since the fluctuations every year are larger than this effect in one century. 84.59.54.27 18:21, 2 April 2007 (UTC)
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