Talk:Saros (astronomy)

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merge with saros 131[edit]

Why is there even a saros 131 page? What about the other 60 or so active saros series? This page will not become better if we add all such details. Tom Peters 22:57, 30 May 2006 (UTC)

Then propose Saros 131 for deletion. I don't know enough about the topic and wanted to throw it open to people more knowledgable than I. As it is. Saros 131 is a orphan article (nothing links to it), the birthday reference is obscure, and the article is generally confusing. I was trying to find articles to link to it and found this one. Thatcher131 02:39, 31 May 2006 (UTC)
Apparently someone has merged saros 131 into the article anyway as an example. However I find it clumsy: repeats info, headings are a mish-mash (no clear hierarchy), numbering and edits thereof are confusing (where are the 1,2,3 1,2,3 sequences promised in the text) etc. Whoever wants this info in the article, please clean up! Tom Peters 11:56, 2 June 2006 (UTC)

?[edit]

The phrase "the saros was discovered by ancient astronomers" is a bit vauge.

According to John P. Pratt's article on the "Symbolism of the Passover" the saros discovery came from "ancient Chaldea"...

Can anyone elaborate / confirm / deny this?

It was certainly known by astronomers in Mesopotamia (Babylonians also known as Chaldeans) several centuries BC as shown by clay tablets. Tom Peters 22:57, 30 May 2006 (UTC)

Series vs Cycles[edit]

Cna this distictin be drawn more clearly? I found the article confusing, espscially as I cme form somthing talking about 1000yr plus cycles to an article which starts with 18 year cycles. Rich Farmbrough 14:29, 3 November 2005 (UTC)

Yes, please, could someone fix this article? It is very, very confusing. 18 years? 1370 years? 24.82.85.97 06:35, 31 January 2006 (UTC)

Read carefully. The cycle lasts 18 years (+ about 11 days): after 18 years a similar eclipse occurs again. There is a series of such eclipses, 18 years apart. Such a series "lives" for about 1370 years on everage: after such a time, there will be no more eclipses multiples of 18 years after the last one. If you can re-formulate the article to make this clearer, please do so. Tom Peters 22:57, 30 May 2006 (UTC)
I agree, the saros cycle section is very confusing and needs to be clarified. The length of the series in tems of years and saros cycles should be explicity defined in the first paragraph of this section. The origin of 1370 year cyclicity needs to be described. The underlying cause as to why series, instead of just cycles, are used needs to be described in words. The numbering system is confusing as well. I don't know enough about this subject to fix this myself. Lunokhod 11:48, 2 January 2007 (UTC)
I elaborated. Is it clear now? Tom Peters 02:22, 3 January 2007 (UTC)
Could you put the subsections "Partial lunar eclipses (Southern edge of shadow)", "Total lunar eclipses", and "Partial lunar eclipses (Northern edge of shadow)" into a table? These should not be in the text portion of this article. It is not clear why there is a "..." between adjacent entries. If you are only going to list 6 partial eclipses, perhaps it would be best to just say in paragraphy form "Examples of partial of lunar eclipses in this cycle are xxx, yyy, and zzz". Lunokhod 10:36, 4 January 2007 (UTC)

Well after 5 years this has been resolved. A saros is a common noun that is by definition a cycle, so the phrase 'saros cycle' is confusingly redundant. Hopefully the article is clearer now. --TimL (talk) 01:29, 24 June 2011 (UTC)

astrology link?[edit]

I noticed that a link has been added to http://www2.bitstream.net/~bunlion/bpi/EclSaros.html which is written by an astrologer, who uses some astrological terms and notation and elaborates on zoodiacal signs and divination of eclipses. Apart from the astrology I do not find much factually wrong with that page (except that "saros" is NOT derived from a Greek word meaning "to repeat": the Greek verb saroein means "to sweep clean". Halley took it from the Suda lexicon, which garbled the facts. The Bab. SAR meant something like "universe", or as a number, 3600); but it adds little that is not or can not be on this page, and I find it odd to refer to astrological pages. Tom Peters 01:27, 8 January 2007 (UTC)

I don't have an opinion as to whether this link is removed of not. I only added this because I thought that the first half of the external link did a better (though more lengthy) job of descrbing the Saros cycle that this wiki topic did. I don't necessarily have a problem with providing a link with astrological significations, as eclipse cycles (especially when they are approximate) have more to do with historical and cultural issues than science. If more good quality external links were found, these could be organized under "astrology", "history", etc. Lunokhod 10:17, 8 January 2007 (UTC)
Oh well. Reading this and that page, I think I see your point. It's a matter of sequence: saros (and inex etc.) are spin-offs from the more generic eclipse cycle, so this page does not repeat the explanations how an eclipse cycle works from the eclipse cycle page. Also this is a merge with a separate page for saros series 131 . I'm afraid that if this page is made more self-sufficient by repeating material, then soon someone will propose a merge with eclipse cycle; but then other pages need to be merged in too; and then that page becomes too long, and someone else will propose a split. I've seen these dynamics happen in Wikipedia ad nauseam. I believe the general preference is to keep articles manageably short, and spawn expansive sections to a main article (see {{main| }}). Since all these cycles have names accepted in literature, I believe in this case separate lemmata are appropriate. Anyway, hence the link back to eclipse cycle at the begin of the this article. Tom Peters 12:39, 8 January 2007 (UTC)
Don't worry, I don't think that its a good idea to merge eclipse cycle with this page. In the next couple of days I'm going to try to expand the explanation here a bit, and slim down the 131 example. And I really don't mind if you delete the link if you don't like it. If I would have read the page to the bottom where the astrology stuff was, I probably wouldn't have added it. Lunokhod 16:48, 8 January 2007 (UTC)

inter-article redundancies[edit]

After Lunokhod's rewrite, this page now contains much explanation not only how eclipses recur, but also why an eclipse occurs. Much of this is also treated in eclipse, solar eclipse, lunar eclipse, and eclipse cycle. Do we want, and our readers need, this redundancy, i.e. do Wikipedia articles need to be self-sufficient? Or do we design some hierarchy where a page (like this) elaborates on a concept treated elsewhere? Tom Peters 15:27, 10 January 2007 (UTC)

"last paragraph"[edit]

Lunokhod asks whether the last paragraph in the section on Saros series is necessary. It gives the references for the Saros series statistics and identification numbers; that's why it was preceding the discussion of these data. Lunokhod, you requested sources for every factoid, so I'd say keep them (including specific reference to the table in Meeus's latest book). Tom Peters 14:52, 12 January 2007 (UTC)

"Lunar eclipse series are not as long-lived."?[edit]

Could someone explain why lunar Saros series are not as long lived as solar ones? It appears to me that the series would have the same length, as the only difference is that one occurs at the ascending node, and the other at the descending node. Also, given that the shadow of the Earth is larger than that of the Moon, I would expect that a lunar Saros series might even be a bit longer than a solar Saros series. Lunokhod 11:11, 19 January 2007 (UTC)

I could, but there are several approaches or levels to describe this, and an explanation would be longish. See Newcomb 1882. Simply I think it is essentially due to this: a total solar eclipse is counted if even a part of the lunar umbra touches the Earth, which is much bigger than the Moon. A total lunar eclipse is only counted if the whole Moon enters the shadow of the Earth, which diameter is somewhat smaller than the Earth itself (shadow cone angle = solar parallax = 8.8"); a partial lunar eclipse will be a total solar eclipse as seen from part of the Moon, but is appreciated differently as seen from the Earth. So the requirements and constraints are tighter for lunar than for solar eclipses. Anyway it is a purely phenomenological observation: the Saros series as collected and studied by Oppolzer, van den Bergh, Meeus, et alii, show that for lunar eclipses they do not last as long as for solar eclipses. I made a short general remark because I couldn't find a specific statement in literature of someone who counted the statistics. Also mind that the quoted longevity of solar Sarosses depends on the compilation that you look at. The 3000-year or so intervals that have been completely computed, contain only about 100 complete Saros series; if you use another interval you may include or loose some series and change the extrema. Tom Peters 13:22, 20 January 2007 (UTC)
Basically, the statement "Lunar eclipse series are not as long-lived" refers to series involving UMBRAL lunar eclipses. If PENUMBRAL eclipses are included, then the series are virtually equal, with lunar eclipses having a very slight edge. Glenn L (talk) 02:20, 20 December 2007 (UTC)

Correspondence of Solar and Lunar saros[edit]

It may be worth noting the correspondence between the Solar and Lunar saros series. For example, the long-duration eclipse of 1991 July 11 was a part of solar eclipse Saros 136. This was followed half a Saros later (about 9 years and 5 days) by the long-duration total lunar eclipse of 2000 July 16, which is a member of Lunar eclipse Saros 129. As a general rule, Lunar eclipse Saros X is matched to Solar eclipse Saros X + 7 and both sets of eclipses have similar characteristics. --B.d.mills 12:37, 5 June 2007 (UTC)

After 4 years, this has been addressed. --TimL (talk) 22:21, 9 July 2011 (UTC)

references in number articles like 51 (number) with negative years[edit]

51 (number) currently says:

Based on the Year zero article, I guess that -1407 is supposed to mean 1408 BC and -1105 means 1106 BC. If I'm right about that, then the corresponding entry in the 50 (number) article has already been edited incorrectly, changing -1201 to 1201 BC.

Many other number articles have the same problem. I might go fix them if one of you astronomical-type editors could tell me the correct interpretation. (Assuming the person who added these references was consistent so that a single rule is sufficient to fix them all) ----tcsetattr (talk / contribs) 05:59, 11 July 2007 (UTC)

If you reread the preceding section, then you will see that solar Saros number 51 corresponds to lunar Saros number 44 (L = S - 7), and that lunar Saros number 51 corresponds to solar Saros number 58 (S = L + 7). However, I have corrected the info for lunar Saros number 51 because the last eclipse of that series was +193 July 31, there having been no eclipse on +211 August 12. --Glenn L (talk) 07:17, 5 January 2010 (UTC)

Need to clarify "Origin from SAR"[edit]

This section is confusing, and seems to toss around lots of information without much context. In particular it would seem to assume some knowledge of the relevant discipline within historiography; several terms are used without definition or links ("year of Adam", "the 300-year Babylon", "Venus tablet", "Ramses Papyrus Canon", etc.). The appearance of religious/mythological stuff about Hindu tradition and time being "king over kings" also feels somewhat misplaced. I think some organization is needed, at least. Markjreed (talk) 14:15, 4 August 2008 (UTC)

According to the Microsoft Encarta College Dictionary (2001), the name "saros" is derived from the Babylonian word sāru, meaning "the number 3,600." Hence Halley's "naming error" noted in the article. —Preceding unsigned comment added by Glenn L (talkcontribs) 07:34, 22 July 2009 (UTC)

References in History section[edit]

The history section claims that the Saros cycle was known to the Chaldeans in the last few centuries BC. First, this seems like a very vague date, is it possible to narrow this down to a specific century or at least a range of centuries? Also, the link to the Chaldeans indicates they flourished between the 7th and 6th centuries BC; this is inconsistent with the statement in the article.--RDBury (talk) 22:19, 5 November 2009 (UTC)

Suda and Eusebius[edit]

I added a note about this which was mistakenly reverted as vandalism. I'm sorry I don't have a reference for it offhand, but no-one in the Greek world has any access to Berossus except via Eusebius. Roger Pearse 13:56, 8 February 2011 (UTC)

Move proposal[edit]

I propose moving this article to Saros (astronomy). As 'Saros cycle' is redundant. The suggested name follows precedent for pages that are directed to from disambiguation pages. I'll leave this here for 2 weeks before moving. --TimL (talk) 23:57, 23 June 2011 (UTC)

On second thought, the title is obviously redundant and am moving. --TimL (talk) 00:25, 24 June 2011 (UTC)
That was a short 2 weeks! I disagree. A saros cycle is a type of eclipse cycle, although Tritos doesn't have cycle in its name, it could, and Metonic_cycle does. Since Saros is a disamb page, it makes sense to keep saros cycle, and that's a lot easier to type than Saros (astronomy), which would have to be renamed in all contexts. Tom Ruen (talk) 00:32, 24 June 2011 (UTC)
Not with a redirect, saros cycle is being kept. It's not going away, but the page title and references to 'saros cycle' are. The only thing that needs changing, (which I have already done) is removal of the redundant and confusing phrase 'saros cycle'. Saros (astronomy) is a necessary evil since Saros directs to a disambig page. Links don't have to be fixed, only displayed text. --TimL (talk) 00:42, 24 June 2011 (UTC)
Some additional notes. Metonic is an adjective. So Metonic alone would not make sense. Metonic cycle is correct. Saros is a common noun, which as you know means an eclipse cycle of about 18 years. --TimL (talk) 00:49, 24 June 2011 (UTC)

For the record... (or all about grammar, not astronomy)[edit]

Definition of saros from OAD:

noun Astronomy
a period of about 18 years between repetitions of solar and lunar eclipses.

Saros is the common noun for a period or cycle. Saros should not be capitalized as it is not a proper noun. Yes the entire NASA eclipse website capitalizes saros, but they are incorrect in doing so. Because the very definition of a saros is a kind of cycle, the phrase saros cycle is thus confusingly redundant and should never be used, even more so because saros is a noun, not an adjective. Thanks! --TimL (talk) 01:40, 24 June 2011 (UTC)

lunarsolar saros twins[edit]

Evidently (as mentioned above) each solar saros has a lunar saros as a twin, with events alternating one sar (half saros) apart. Solar saros x is the twin of lunar saros (x-7). It is unfortunate they have different saros numbers. They start at roughly the same time, peak centrally at the same time, have almost exactly the same number of members and are otherwise intimately intertwined, each event alternating 9 years with the other. Why the (x-7)? Seems like it would make sense to give each pair the same saros number. Since we have charts for most of the solar and lunar saros perhaps they should be cross-linked. --TimL (talk) 14:42, 17 July 2011 (UTC)

Blame George van den Bergh, whose 1955 numbering system is still considered canon (pun intended). Also, see my recent reply to your fractional day question on my talk page. — Glenn L (talk) 15:53, 25 July 2011 (UTC)

Super-Saros?[edit]

If a Triple Saros is 54 yrs + 1 mo, then a multiple of 12 of those (649 yrs) would allow the eclipse to be exactly the same: same time of day, same location on the earth, same time of year, same location for the moon.

It seems to make sense to me but I am no astronomer. — Preceding unsigned comment added by 96.227.230.95 (talk) 05:42, 2 August 2011 (UTC)

Theoretically, yes, except for two problems:
(1) The triple saros is about two days longer than 54 years and 1 month, actually nearly 54 years 33 days or 54.09 years. So 11 of these (33 saros cycles) would come closer to an exact number of solar years (595 years minus 3.5 days) than 12 of them (36 cycles or 649 years plus 29.4 days). But more importantly,
(2) The saros series is not infinite, with only "69 to 87 eclipses in each series" according to the article. So your gap, whether 11 or 12 triple saros cycles, would have only two or three eclipses in them, with very different circumstances, although they would of occur at the same time of the year. Good try, however.
If you look at A Catalogue of Eclipse Cycles, you will find a number of true eclipse cycles that do what you are trying to accomplish—some extremely close to an exact number of years—involving combinations of the saros and the inex. — Glenn L (talk) 07:03, 2 August 2011 (UTC)

Bad math[edit]

6585.3213 / 18 ~= 365.85, off by less than one day from 365.242. I fixed the lead, but there are other calculations which might also be wrong based on the original miscalculation. -- Kendrick7talk 19:54, 13 May 2012 (UTC)

I replied on your talk page. The correct calculation is 6585.3213/365.242199. --TimL (talk) 13:28, 14 May 2012 (UTC)
Thanks again! -- Kendrick7talk 04:15, 17 May 2012 (UTC)