Talk:Definition of planet/definition of planet archive 8
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[edit] 'Seven planets' section
This whole section is rather misleading. It's pointless to take all these random quotes from ancient authors when the definition of planet was not a subject of dispute during this period at all. The classical definition of the seven planets was not only "not unheard of", it was the only definition of "planet" in just about every pre-modern culture. Basically, "planet" just meant "light that moves with respect to the celestial sphere". It did not have the implications of being an Earth-like body or anything of the sort.--Pharos 11:46, 16 June 2007 (UTC)
- The earliest sources define a planet differently than the later sources, as far as I can tell. I can't go and say "The ancient Greeks believed there were seven planets" if every primary source I can find on the subject tells me that they didn't.
- EDIT: I just split off another subsection; I hope that makes things clearer. Serendipodous 12:33, 16 June 2007 (UTC)
- I believe you are in error that "the earliest sources define a planet differently than the later sources"; this appears to be a wrong impression on your part from some selections of translated ancient texts. The quotes in the new section you've added are quite ambiguous in character ("planets" in these quotes is likely a gloss for "other planets"), and we're not even sure such wording closely reflects the Ancient Greek original. Now, there should be secondary sources on this: I would like to see some that make note of such a difference between earlier and later classical understandings of "planet", because, frankly I've just never heard of anything like this and it sounds a bit idiosyncratic.--Pharos 05:02, 18 June 2007 (UTC)
- Believe me, I've been looking for secondary sources on this. I'm not trying to push an agenda here; I had no idea about this until I started trying to source the "History" section. The fact is that Ptolemy unequivocally lists five planets distinct from the Sun and Moon. I know this because he has separate sections in the Almagest for "the Sun", "the Moon" and "the Planets". I can see how the Plato and Aristotle references might be considered ambiguous but it's hard to see how you could argue against the lines from Hygius and Manilius. I've been to practically every library in London trying to sort this out. I even contacted a number of professors of the history of astronomy. They agreed that this ambiguity existed, but couldn't offer me any assistance in tracking it down. Serendipodous 05:35, 18 June 2007 (UTC)
- Yeah, I know you're not trying to push an agenda or anything. But I do think in your zealous pursuit of referencing you've unintentionally strayed a little in your interpretation of primary sources, to the point of WP:OR really. Whether classical writers ever used "planets" as a gloss for "lesser planets" in the way that we use "animals" as a gloss for "non-human-animals" is an interesting question, and the idea that there was actually some sort of change in writer's appreciation of this idea over the centuries an even more interesting one. But that is a question for scholars only, not us. Because the fact is that we do have plentiful secondary sources on this, and they all say the ancient Greeks recognized seven planets.--Pharos 06:24, 18 June 2007 (UTC)
- Well, I do have some secondary sources lined up, but unfortunately, the book I'm after is on a 48-hour waiting list. But still, even with secondary sources, I don't think I can ever prove this, not without some work that explicitly mentions the five/seven split (and they are thin on the ground; most books I've read simply take one one conception or the other as a given); so I think the best thing to do, whether I find the right primary sources or not, is to emphasise the ambiguity in the term, rather than make such a formal division (the whole point of this article is, after all, the ambiguity inherent in the word "planet"). That should, I hope, lessen the ORish element in the current draft. Serendipodous 15:41, 18 June 2007 (UTC)
- Yeah, I know you're not trying to push an agenda or anything. But I do think in your zealous pursuit of referencing you've unintentionally strayed a little in your interpretation of primary sources, to the point of WP:OR really. Whether classical writers ever used "planets" as a gloss for "lesser planets" in the way that we use "animals" as a gloss for "non-human-animals" is an interesting question, and the idea that there was actually some sort of change in writer's appreciation of this idea over the centuries an even more interesting one. But that is a question for scholars only, not us. Because the fact is that we do have plentiful secondary sources on this, and they all say the ancient Greeks recognized seven planets.--Pharos 06:24, 18 June 2007 (UTC)
- Believe me, I've been looking for secondary sources on this. I'm not trying to push an agenda here; I had no idea about this until I started trying to source the "History" section. The fact is that Ptolemy unequivocally lists five planets distinct from the Sun and Moon. I know this because he has separate sections in the Almagest for "the Sun", "the Moon" and "the Planets". I can see how the Plato and Aristotle references might be considered ambiguous but it's hard to see how you could argue against the lines from Hygius and Manilius. I've been to practically every library in London trying to sort this out. I even contacted a number of professors of the history of astronomy. They agreed that this ambiguity existed, but couldn't offer me any assistance in tracking it down. Serendipodous 05:35, 18 June 2007 (UTC)
- I believe you are in error that "the earliest sources define a planet differently than the later sources"; this appears to be a wrong impression on your part from some selections of translated ancient texts. The quotes in the new section you've added are quite ambiguous in character ("planets" in these quotes is likely a gloss for "other planets"), and we're not even sure such wording closely reflects the Ancient Greek original. Now, there should be secondary sources on this: I would like to see some that make note of such a difference between earlier and later classical understandings of "planet", because, frankly I've just never heard of anything like this and it sounds a bit idiosyncratic.--Pharos 05:02, 18 June 2007 (UTC)
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- Do you have JSTOR access? I don't have access on my home computer. I'dlike to have a look at this. The online secondary sources are maddening on this; some say seven planets, while others say "The sun, the moon and the planets". It's interesting to note that "ancient greek" "five planets" produces exactly the same number of hits on Google Scholar as "ancient Greek" "seven planets" Serendipodous 16:49, 18 June 2007 (UTC)
- Yes, I do have JSTOR access. Here is the most relevant line in that text, speaking of Ptolemy, That he was aware that they offered greater difficulty than the sun and moon is apparent from his reference to them as "the five planets," although it was customary to speak of seven planets. I will gladly send you the full PDF if you e-mail me for it. This is an interesting little note on the Almagest, and the first I've seen that discusses this use of terminology, but I think it's important to recognize that any divergent meaning of "planet" in Ptolemy is more of a colloquial or technical shorthand than a radically different cosmology.
- Do you have JSTOR access? I don't have access on my home computer. I'dlike to have a look at this. The online secondary sources are maddening on this; some say seven planets, while others say "The sun, the moon and the planets". It's interesting to note that "ancient greek" "five planets" produces exactly the same number of hits on Google Scholar as "ancient Greek" "seven planets" Serendipodous 16:49, 18 June 2007 (UTC)
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- In particular, I don't see any evidence of someone who uses the phrase "five planets" ever disagreeing with someone who uses the phrase "seven planets", and classical authors were certainly quick to point out others' supposed errors. By the way, note that the author on JSTOR says it was "customary to speak of seven planets" at the time of Ptolemy, so I don't see any support for the "five planets first" hypothesis there.--Pharos 00:23, 19 June 2007 (UTC)
- Ptolemy was rather late; the Almagest was written in the second century, long after the shift from the Greek to the Roman world. Most of the "seven planet" quotes I've been able to locate are either later, Roman, or both.
- In particular, I don't see any evidence of someone who uses the phrase "five planets" ever disagreeing with someone who uses the phrase "seven planets", and classical authors were certainly quick to point out others' supposed errors. By the way, note that the author on JSTOR says it was "customary to speak of seven planets" at the time of Ptolemy, so I don't see any support for the "five planets first" hypothesis there.--Pharos 00:23, 19 June 2007 (UTC)
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- The main problem I have with this whole issue is that there doesn't appear to be a way we can resolve it without resorting to OR. We may find a large number of sources mentioning seven planets, but that won't answer the question as to why so many sources refer to five planets. Claiming that it is a colloquial shift is just as much a supposition as claiming it was a different cosmology. Serendipodous 07:38, 19 June 2007 (UTC)
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- You both make good points and I don't really have a good solution to offer. It could be pointed out, however, that there were recognized differences between the Sun/Moon and the five planets. For example, estimates were made of the distances to the Sun and Moon, but not for the other planets. Also the retrograde motions of the outer planets required the introduction of epicycles by Ptolemy. He used the same mechanism for Venus and Mercury, but locked the centers of the epicycles to the direction of the Sun. So perhaps therein lies some of the differences in interpretation? (His five planets were the wandering stars that employed epicycles.) Otherwise I don't know. — RJH (talk) 15:00, 19 June 2007 (UTC)
- One of the secondary sources I've found on this makes the point that the difference between the planets and the Sun and Moon was retrograde. I'll need the source that's currently on hold to back it up, so I won't be able to insert it until Wednesday. Serendipodous 15:25, 19 June 2007 (UTC)
- You both make good points and I don't really have a good solution to offer. It could be pointed out, however, that there were recognized differences between the Sun/Moon and the five planets. For example, estimates were made of the distances to the Sun and Moon, but not for the other planets. Also the retrograde motions of the outer planets required the introduction of epicycles by Ptolemy. He used the same mechanism for Venus and Mercury, but locked the centers of the epicycles to the direction of the Sun. So perhaps therein lies some of the differences in interpretation? (His five planets were the wandering stars that employed epicycles.) Otherwise I don't know. — RJH (talk) 15:00, 19 June 2007 (UTC)
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- I still think the characterization of the issue is quite problematic. You and I as non-scholars in this field are just not competent to make a comprehensive survey of ancient astronomical writings. We have no authority to make statements about relative preponderances of terminology, nor to make novel observations from primary sources such as that "five planets" precedes "seven planets" (an observation that as far I can tell has not been made anywhere else). The most we can say, in my opinion, is that "seven planets" was customary, but that "five planets" was used sometimes and that the ancient Greeks treated the Sun and Moon differently from the planets in certain ways (without asserting that this is or is not the reason behind terminology differences). When there are virtually no secondary sources on this, I feel we are forced to treat this as academia has treated it, that is largely as a non-issue.--Pharos 02:20, 28 June 2007 (UTC)
- I can't really ignore this though; it ties in with the lead sentence for this section: "The word planet has meant many different things in its long life, often simultaneously." EDIT: OK, I've ambiguised it a little more. Serendipodous 07:22, 28 June 2007 (UTC)
[edit] Further research on 'five planets' vs. 'seven planets'
OK, I think I've found one secondary source that seems to parallel your influence-of-astrology theory. See Alexander von Humboldt's Cosmos (section starting pg. 297). I also found something interesting on pg. 28 of Studies in Dante, which references George Cornewall Lewis's Survey of the Astronomy of the Ancients (unfortunately not online) to the point that the earlier Greeks had a different ordering of the planets, which placed the Sun and Moon in a separate "zone" closer to the Earth, rather than being separated by the orbits of Mercury and Venus (this change is actually related to the further advance of science, but who knows it may be related to the same gestalt of the influence of astrology).--Pharos 16:04, 28 June 2007 (UTC)
- How extraordinary; I had Cosmos on my reading list at the British Library but it got sent back. I knew it referred to the issue but I couldn't find a direct quotation. I've also been trying to locate The History and Practice of Ancient Astronomy by James Evans. Apparently it delves into the issue. It's too late today, but I'll try and get an early morning on this tomorrow. Serendipodous 16:09, 28 June 2007 (UTC)
- You do realize you can read Cosmos online, right?--Pharos 16:25, 28 June 2007 (UTC)
- Actually, reading it, it was a different Cosmos. Still, the more we can find, the better. And Humboldt is about as cast iron a source as you could hope for. Serendipodous 16:28, 28 June 2007 (UTC)
- Shouldn't we source it to Humboldt, then?--Pharos 03:39, 16 July 2007 (UTC)
- I haven't had time to work on this yet, but I will be going to the British Library today to track down sources. By all means, source it to Humboldt as well, but I would like to get some more backup. Serendipodous 07:08, 16 July 2007 (UTC)
- Shouldn't we source it to Humboldt, then?--Pharos 03:39, 16 July 2007 (UTC)
- Actually, reading it, it was a different Cosmos. Still, the more we can find, the better. And Humboldt is about as cast iron a source as you could hope for. Serendipodous 16:28, 28 June 2007 (UTC)
- You do realize you can read Cosmos online, right?--Pharos 16:25, 28 June 2007 (UTC)
OK. I've managed to locate a source that, while it doesn't refer to the dichotomy precisely (rather infuriatingly, it refers to Pliny without mentioning that Pliny states there are seven planets), does nonetheless confirm that the Greeks treated the planets differently from the Sun and the Moon. It is: The History and Practice of Ancient Astronomy by James Evans, Oxford University Press 1998, p. 296-7:
The Greeks of the seventh century BC were not even sure how many planets there were. The Greeks had two different names for Venus: it was called Hesperos [evening (star)] in its guise as evening star and Phosphoros (light bringer) when it appeared as morning star. Some asserted that Pythagoras (sixth century BC) was the first to realise that themorning and evening stars were one, while others give the credit to Parmenides (fifth century).
The Greeks considered the planets to be divine, living beings who moved by their own wills. Each planet had a proper name but was also called the star of a certain god:'
- Greek name____Translation____Greek god____Roman god
- Phainon_________Shiner_________Kronos_______Saturn
- Phaethon________Bright one_____Zeus_________Jupiter
- Pyroeis_________fiery one______Ares_________Mars
- Phospohoros_____light bringer__Aphrodite____Venus
- Stilbon_________gleamer________Hermes_______Mercury
...To the early Greeks, the Sun, Moon and fixed stars were far more important than were the planets. The motion of the Sun was intimately connected with the annual cycle of agricultural labors. The phases of the Moon governed the reconing of months. And the heliacal risings and settings of the stars told the time of the year. The irregular and nonrepeating motions of the planets had no such direct utility. So it is not surprising that Hesiod's Works and Days (ca. 650 BC) which contains a good deal of practial lore about the Sun, Moon and stars, makes no mention of the planets.
Serendipodous 19:16, 16 July 2007 (UTC)
- There certainly are several sources that point vaguely in this direction, but Humboldt as far as I can tell is the only one to make an explicit statement along such lines. Yes, he is problematic as a source because he is after all "one 19th century scholar", and men of such description have been known to propgate some strange theories. But we shouldn't just gives hints of what we're trying to say, we should say it. And if we say it—barring better, more modern, secondary sources to be discovered—we'll have to rely on old Humboldt to some extent.--Pharos 00:15, 23 July 2007 (UTC)
- OK, Humboldt has been added. Thanks for tracking him down. I'd like to think I can finally put this page to rest now but somehow I doubt this will be its final controversy. Serendipodous 12:45, 23 July 2007 (UTC)
