Early Greek knowledge of the planets

buss Eanes, 4 DN CK WELL, are Ax Early Greek Knowledge of the Planets. By Peter J. Bicknell. Monash University, Clayton, Australia. In a recent article! D.R. Dicks impugns the doxographical notices? which indicate that Anaximander distinguished planets from fixed stars and also the view of many modern scholars? that Anaximenes did the same.* In Dicxs’ opinion, it is doubtful whether the planets were recognized as such by the Greeks before the fifth century B.C.; “careful observation over an extended period would be necessary to differentiate them from the fixed stars (compare Venus, the brightest planet, as the morning and evening stars in Homer)”, 4 D. R. Dicks, “Solstices, Equinoxes and the Presocratics”, JHS 86 (1966), p. 30. : 2 Aetius 2.15.6 (DK.12 A 18) where Anaximander is coupled with Metrodoros of Chios and Krates. A reference to the planets as well as that to the moon has clearly fallen out of the text of Hippolytus Ref. 1.6.5. (DK.r2 Arr) at DE. p. 84 line 15. 3 For example, Sir THOMAS Heats, Aristarchos of Samos, pp. 42-3, and W.K. C. GUTERIE, A History of Greek Philosophy, vol. 1, pp. 135 ff. Their view is based on Aetius 2.14.3 (DK.13 A 14) where they emend vor to évious and take the dorpa “fixed like nails in the crystalline” as fixed stars and the dorépas compared to fiery leaves as the planets. The planets being made free-floating, Anaximenes could explain their motion relative to the fixed stars in the same way as he accounted for declination of the moon and the movement of the sun between the solstices—as due to their being blown from a consistent orbit by gusts of wind (Aetius 2.23.1—DK. 13 À 15), Some (for example, J. LONGRIGG, “kpvoraAdoerdös” CQ 59 (1965), pp. 249-251) have argued that a crystalline heaven studded with fixed stars is not Anaximenean and that Aetius is mistaken. It is true that the Pseudo-Plutarch of the Stromateis and Hippolytus do not mention it in their extracts on Anaximenes, but, as K. FREEMAN (Companion. to Diels-Kranz, p. 72) pointed out, the comparison of the stars in the crystalline firmament to nails has an unmistakably Milesian flavour. See also note 13 below. 5 See, for example, Iliad 22.318 (Hesperos) and Odyssey 13. 93~4.

Set.out step by step, Dicks’ argument would seem to run as follows. i. Venus is the brightest planet and until Venus was recognized as a planet no other celestial body could have been. 2. Recognition of the planetary nature of Venus implies recognition of the identity of the morning and evening stars. 3. The first Greek to identify the morning and evening stars was Parmenides® who was at work at the beginning of the fifth century. 4. No planet, consequently, can have been recognized as such by the Greeks before the fifth century B.C. In what follows, I shall suggest that step 2 is fallacious; the morning and evening stars, not identified until Parmenides, were separately distinguished from the fixed stars at least as early as the seventh century. In addition I hope to show beyond reasonable doubt that the planetary nature of at least one other heavenly object was recognized by the time of Anaximander and Anaximenes. At Laws 821 c Plato puts the following remarks into the mouth of Kleinias the Cretan, one of his shadowy interlocutors; kai tov Eomepov Kal dAAas twas oddémore lóvras eis Toy aùròv ev yap In TÔ Pip moMaxıs éwpara Kai adròs Tov Te Ewopopov Spavras raûra del mdvres Euverioraueda. Spdpov, GAAA srdvry mAavwuevovs, Tov dé “H)uov mov Kal geAnvnv (“during my life I have often observed how Eosphoros and Hesperos and certain other celestial bodies never travel on the A 40a); Diogenes Laertius 9.23 (cf. 8.14 as & Aetius 2.15.4 (DK. 28 emended by CASAUBON) on the authority of Favorinus and Callimachos. Diogenes (loc. cit; cf. Pliny N.H. 2.37) notes an alternative ascription of the identification to Pythagoras. This was either due to a mistaken attribution of Parmenides’ poem (see Diogenes 9.23; does another wrong ascription lie behind the notion of the author of CRAMER, Inedita 3. 413. 16 that “recognition of the identity of Eosphoros-and Hesperos was first made by IByKos of Rhegion?), or to the practice of members of the Pythagorean brotherhood (of which Parmenides was:'a member— Diogenes 9.21; Strabo 6.252; Proklos in Parm. 1. p. 619.4; Photios Bibl. c. 249) of ascribing’ their own discoveries to the master (see Cicero ND. 1.10 and Diogenes 8.46). 3 urn érès: im ae EARLY GREEK KNOWLEDGE OF THE PLANETS 49 same path, but wander all over the place; in the case of the sun It was evidently possible for Plato to conceive of observers and moon, of course, we all know that they behave like this all the time.). : of the heavens who, while realising that both the morning and evening ‘stars’ changed their position relative to the fixed stars, were unaware of or did not accept their identity. For such, Eosphoros and Hesperos were two different planets. It is likely, indeed certain, that Venus in its two aspects would have been the first of the planets to be recognized by the Greeks as such, both on account of its great brilliance,” and of the rapidity of its West to East motion on the celestial sphere. It is simply not true that such recognition cannot have preceeded realization that Hesperos and Fosphoros were one and the same body. The change of position of Venus relative to the fixed stars is conspicuous over even a fraction of the period during which it is morning or evening star, and it is scarcely conceivable that it passed unnoticed century. by farmers, sailors and early physikoi until as late as the fifth Although not identified, Eosphoros and Hesperos cannot but have been distinguished from the fixed stars at a very early date, and distinguished they certainly were by the seventh century. In two lines (381-2) of the Theogony, Hesiod writes rods d£ yer’ dorépa. rikrev éwopôpor ’Hpvyévera dorpa re Aaurerdwvra, rd 7’ odpavòs eorepdvwrat It is difficult, and it would surely be perverse, to resist the conclusion that dorépa and dorpa are deliberately contrasted.® Hesiod regarded Eosphoros as different to the fixed stars, the constellations with which the sky is wreathed. The obvious difference is that the position of Eosphoros alters with respect to its stellar neighbours. Hesiod, then, recognized that the morning star is a wanderer and he must obviously have recognized that the same was the case with its evening counterpart. Exactly how much farther back than Hesiod knowledge of the planetary 1 Note Iliad 22.318; Sappho frag. 32E; Pindar Isthmian 4.24. ® Compare West’s remark in his commentary, p. 271.

it is imnature of Venus Eosphoros and Venus Hesperos goes, possible to say.? has Choiroboskos, a grammarian of the sixth century A.D. wAavnTow the following note on the word pecdvué; els Tv érra yopos. Tapa Tots ITvdayopeioıs övondlera péuvmrai Z'rnoi (Choiroboskos at Bekker Anekdota 3.1397). whose dates were sively that overlooked by As far as I am aware, this passage has been at least as early as the lifetime of Stesichoros, historians of astronomy. It surely shows quite conclu and Hesp632-556, at least one other planet besides Eosphoros is applicable eros had been recognized. The name Mesonux which guish the to all of the outer planets, was clearly chosen to distin inner first of them of which the Greks became aware from the them, is planet Venus (Eosphoros plus Hesperos), which, unlike identificanever observed in the middle of the night. A possible but Jupiter tion of Mesonux is with the conspicuous Jupiter, s Mars whose moves slowly among the stars and probability favour ic West to East motion is much more rapid and which at perihel est opposition (when dramatic retrogression occurs) is the bright dorépes and ® Homeric usage appears to make uo distinction between per’ dorpéor vurrös dorpa; at Iliad 22.317 Hesperos is an dorip but elo (at Theognis 1040, dpody@; at Iliad 5.5 and elsewhere Sirius is an dorjp word can also be used of a it is worth noting, Sirius is an dorpov) which that, in the case of the lyric nce necessarily fireball (Tliad 4. 75-77). Does this terminological indiffere Venus and the imply that the poet was unaware of a distinction between to suppose similar fixed stars? Hardly: if it did, we would then have (frag. 32 E) ignorance on the part of the post-Hesiodic Sappho who writes worse, on the part of Hesperos as dorépuv mévrur 8 KdÀtoros, and, much ual advances of his of the still later Pindar who was close to the intellect as Banròs darpois ev age; Pindar (Isthmian 4.24) describes Hesperos for observing and gow. Unlike Hesiod, who had practical reasons who compiled an distinguishing the motions of the heavenly bodies and ioned to observe Astrologia, Sappho and Pindar were pure poets, uncondit terminological niceties. Add to this the fact of vocabulary. The poet, metrical exigency is a powerful determinant their vocabulary Homeridai too were artists only, and it might be argued that the fact that darip, also was determined by special factors, in their case by formulae going dorépes and dorpa were indiscriminately incorporated into back to a time before any planets had been distinguished. pnt nn le EARLY GREEK KNOWLEDGE OF THE PLANETS 5I object in the sky except for Venus. The ambiguous name Mesonux, generally abandoned sometime after the discovery of other outer planets in favour of “Puroeis (aster)”!° (the fiery planet)" or the “aster of Ares”, was apparently retained by certain Pythagoreans. that Anaximander distinguished planets from fixed stars, and It will be clear by now that there is not the slightest reason to doubt the doxographers’ categorical statements to the effect the implication of their evidence that Anaximenes held the former to be free-floating fiery discs like the sun and moon, subject like them to wind-induced perturbations, in distinction from the fixed stars attached to a crystalline firmament The planets of the pre-Parmenidean Ionians!* will have numbered at least three; Venus in its two aspects and Mars. They could have known of the planetary nature of Jupiter also, but its recognition is just as likely to have post-dated Parmenides’ identification of Eosphoros and Hesperos and a temporary reduction, for those who were aware of and who accepted it, of the number of known — Saturn, Jupiter, Mars, Mercury, Venus, Sun, Moon—rather than the 10 The earliest appearance of zupdas as Mars is in the Pseudo-Aristotelian de Mundo (399 a 9) which probably dates to the third century B.C. (for example, at 392 a 25 ff. the planets are given in the ‘Pythagorean’ order is little earlier than the de Mundo, then the name the Epinomis author ‘Chaldean’—Saturu, Jupiter, Mars, Sun, Venus, Mercury, Moon). By 200 B.C. the former order was all but obsolete. At Epinomis 986 e it is stated that our Mercury, a few lines later described as Hermes’ planet, has as yet no name. The implication is that the long known planets, Venus and Mars, did have names in Plato’s time, as well as divine associations. If Puroeis 617 €. | has in mind is Mesonux. 11 Is the allusion to fire's brightness or to their red glow? The earliest extant Greek reference to the redness of ‘The Red Planet’ is Plato Republic 12 See note 21 below. 13 See note 3 above. Ion of Chios (lyric fragment 2E) writes of ’Aoiov depopdırav dorépa. Has Ion Anaximenes’ description of Venus in mind? Note the employment of dornp. 4 Anaximander, Anaximenes, Xenophanes and Herakleitos. The doxography does not mention any planetary theory in connection with the two last mentioned.

EARLY GREEK KNOWLEDGE OF THE PLANETS extant in this sense at de mundo 392 a 25—GUNDEL, RE Planeten col. 2032 is certainly wrong in regarding it as standing for Venus at Theogony 987; Aristarchos’ pvyov makes more sense than the véywv of the MSS) and paivur (first extant thus at de mundo, loc. cit.) for Jupiter and Saturn are also Babylonian derivations rendering Kaimanu and Daipinu respectively. with Herakles. It is conceivable that the appellations of paédwy (first Planets were on occasion associated with different deities, either on the basis of non-Babylonian foreign equations or with astrological motivation. Besides the orthodox affiliations the de mundo reports associations of Mercury with Apollo (cf. Pliny NH. 2.39) and Venus with Hera. Of Venus, Pliny NH. 2.37 writes that there had been great competition in giving it a name; “some have called it Juno (Hera), others Isis (cf. Ptolemy, Tetrabibl. 2.3.23), others Mater Deum (no association with Athene is ever mentioned as Velikovsky would have done well to note!). Again according to Pliny (cf. Theon 130 and Macrobius Sat. 1.19.7) Mars was by some connected Hermes; Epinomis 987 b ff.—Aphrodite, Hermes, Kronos, Zeus and Ares. For the same associations in Aristotle, see Metaph. 10736 32 ff. Some of the about the existence of extra planets. Nigidius’ reasons were probably astrological; the Hamburg school of astrology founded by ALFRED WITTE some 40 years ago takes into account the motions of eight hypothetical trans-Neptunian planets in compiling horoscopes! 20 See Diogenes 9.35; Aelian VH. 4.20, and earlier and more reliable, Strabo 15.703. # The associations with divinities appear first in Plato; see Timaios 38 d— 1.3.16 and Nigidius Figulus (see Aulus Gellius 14. 11-12) also speculated cometary theory see Aristotle loc. cit. Aetius 3.2.2.—DK, 59 A 81 etc.). Anaxagoras, of course, did not know of all of the canonical five. Cleomedes too that the divine associations of the planets among the Greeks and thence the Romans may be owed; Hermes (Mercury), Aphrodite (Venus), Ares (Mars), Zeus (Jupiter), Kronos (Saturn) are, of course, the closest equivalents the Greeks could find for Nabu, Ishtar, Nergal, Marduk and Ninib respectively, whom the Babylonians linked with the five planets of the ancient world. 53 PETER J. BICKNELL not the details of their motions, to the Greeks, having learnt of it in the course of his travels in Babylonia. It is to Demokritos 52 planets from three to two, Hesperos—Eosphoros!® (Venus) and Mesonux (Mars). From the Epinomis!5 we learn that the elusive and inconspicuous Mercury,” the other inner planet, had not long been recognized when that dialogue was written. The same would certainly be true of Saturn and it could be true of Jupiter.!? It is conceivable that it was Demokritos who revealed their existence,!® although 48 The names Hesperos and Eosphoros (or its variant—see Ion frag. 2 and inner planet? Not, I suggest, if his knowledge of this planet was based Euripides frag. 929) persisted in use long after their identification as one body: see Ion and Euripides, loc. cit.: Euripides Ion 1149; Plato Timaios 39c; Aristotle EN 1129b 28 and Metaph. 987a. 16 Epinomis 986c. The dialogue I take to be a late effort of Plato reworked by Philip of Opus. 17 The planet is only seen at near greatest elongation; it begins to come into view some 17 to ro days before evening elongation and vanishes in 6-7 days. This occurs every 116 days. The planet can be observed in evening and morning twilight low down near the horizon. 18 Saturn takes 29 years to complete a circle of the zodiac. A retrogression occurs once every 378 days. Jupiter circles the zodiac in 12 years and retrogression occurs once every 399 days. 19 According to Seneca NQ. 7.3.2., Democritus ... subtilissimus antiquorum omnium suspicari se ait plures stellas esse quae currant, sed nec numerum illarum posuit nec nomina, nondum comprehensis quinque siderum cursibus. The meaning is surely that Demokritos knew of the five planets Saturn, Jupiter, Mars, Venus and Mercury, but not of their motions (Plato at Timaios 39c stresses how restricted such knowledge was at a time when Eudoxos and others were having some success with the problem), not that he did not even know of all of the canonical five. It could, I suppose, be argued however that Aetius 2.15.3 (DK. 68 A 86), if trustworthy, militates against crediting him with knowledge of Mercury, especially as, if Hippolytus (Ref. 1.13.4= DK,68 A 40) is correct, he paid special attention to relative distances of the planets, According to Aetius À. rd mèr dmlavj apdrov pera 8€ Tadra rots wAaviras Ep’ ols MA pwopdpov cedAtvnv. Ought he not to have placed Mercury between sun and moon together with its fellow only on Babylonian hearsay. Eudoxos was probably the first to study Mercury's motion empirically; he calculated a synodic period of 110 days— Simplicius de Caelo 495 ff. Demokritos speculation (presumably in his book on the planets—Thrasyllos at Diogenes 9.46) about the existence of other planets besides the canonical five was no doubt bound up with a view first enunciated by Anaxagoras (see Aristotle Meteor. 3426 b25 etc.) that comets were conjunctions of one or more planets (for Demokritos ndr eere dv ve sen es zeef VA ate ce CERTA

ADDITIONAL NOTES A. In his article, Dicks, to say the least, comes close to arguing doradurrous dorépas yravan Kal Tas amooräceıs auTrav that the fact that the Greek word rAavÿrys does not appear in the sense of “planet” until Xenophon Mem. 4.7.5. tells in favour of his extreme view as to the lateness of recognition of planets among the Greeks. The fact is surely that physikoi found sufficient for their purpose such periphrases as mAavwpevor dorepes or mrÀavyrà dorpa?? and felt no need to add a new sense” to mAavyTys. The Xenophon passage runs as follows: rods mhavyras Te kat amo THs yfjs Kal Tds mepiddous Kal tas airias aùróv Cyrotvras kararpißeoda:ioyup®s dmérperev (the subject is Sokrates). One gets the impression that study of and speculation about the planets was long and well established at the time of his writing. B. CARDINI?S is doubtless right in explaining that Persephone Porphyry, Vit. Pythag. 41: &eye (the subject is Pythagoras) à 8H ei méov ’ApıororeAns dd twa Kal puorik Tpórmp ouuBolküs, (frag. 196 Rose’) dvéypaber, olov örı Tv Ddharrar pev ékdÂer elvaı Sdxpvoy, tas 8è äpkrous ‘Péas Xeipas, Tijv Bé IIAeıdda Movoóv Mopav, robs de mAavnras KUvas THs Llepoepövis … equals Selene equals Artemis. Whoever of the Pythagoreans really formulated the definition, it sounds primitive enough as the turn of the sixth century, Greek recognition of planets. and may be taken as further evidence of early, at least as early 22 See, for example, Plato Timaios 38c; Laws 821 b and c: Aristotle Metaph. 1073b 22; Meteor 342b 28. © 5% For the normal sense, see Plato Rep. 371 d. % Xenophon may have Anaxagoras especially in mind on whom see note 19 above, and also perhaps Empedokles who held views about the planets similar to those of Anaximenes (see Aetius 2:13.1I—DE. 31 A 54). 25 CARDINI, Pitagorici—Testimonianze e Frammenti, vol. 3, p. 245.