BMCR 2000.12.10

Astra Caesarum: Astronomia, astrologia e catasterismo da Cesare a Domiziano

, Astra Caesarum : astronomia, astrologia e catasterismo da Cesare a Domiziano. Testi e studi di cultura classica ; 16. Pisa: ETS, 1996. 191 pages ; 22 cm.. ISBN 8877419326. L.20,000.

This book1 expands upon and refines views presented in an earlier monograph by D. ( Astra Caesarum: Note sul catasterismo a Roma. Chieti, 1989), which is a very scarce item in this country.2 The 1996 publication appeared too late for me to take it into account in the book I wrote on the comet of 44 BC in collaboration with my colleague in Physics, Lewis Licht (henceforth R-L)3 and D.’s 1989 publication was not known to me until the later book came out. Although the book under review examines a longer span of history than R-L covering the period from the comet of 44 (the sidus Iulium) through the reign of Domitian, both books devote a considerable portion of their discussions to the comet of 44. Roughly half of D.’s work is given over to that comet, a topic which sets the stage for the two remaining chapters. By concentrating my review on D.’s treatment of the sidus Iulium, I believe that it is possible to convey the strengths and weaknesses of this study which addresses the important role played by the stars in furthering the power of Augustus and his successors.

The work opens with a general introduction in which D. draws attention to the prominence enjoyed by astronomy/astrology in the Greco-Roman world (pp. 13-27). The various links between the stars and the world of man, in life (as omens and timekeepers) and after death (as signs of deification: catasterism), are succinctly presented. The author then proceeds in three chapters to relate the way in which astronomy/astrology had significance for Julius Caesar (I. “Cesare e le stelle”, pp. 29-99), for Augustus (II. “Il cielo di Augusto”, pp. 101-38), and finally for the remaining Julio-Claudians and Flavian dynasty (III. “Il cielo degli imperatori da Augusto a Domiziano”, pp. 139-80). The first chapter is divided into two parts, on the comet of 44 (pp. 29-85) and on Caesar’s reform of the calendar and the astronomical work De astris attributed to Caesar (pp. 85-99).

In his discussion of the comet of 44, although D rightly acknowledges (p. 31, 35) that most ancient sources depend upon the account given by Octavian/Augustus in his Memoirs, D. occasionally appears to lose sight of this fact when he treats clearly derivative sources as if they had some independent evidentiary value (e.g., p. 34 n. 18, Plut. Caes. 69.3 on the size of the comet, and Hor. Carm. 1.12.46 on its brilliance, although Horace’s reference to the brilliance of the sidus Iulium is doubtless intended as a comment on the splendor of Augustus, not the comet4). Although D. occasionally makes good use of other sources to supplement Octavian’s version (e.g., p. 34, the description of the comet’s physical appearance by Baebius Macer, most likely a contemporary observer), D. does not extract from the few independent strands of the tradition all that they can tell us, nor is D. prepared to entertain any significant departures from Octavian’s account. For instance, D. (p. 31 n. 8) curtly dismisses the evidence furnished by Servius (on Ecl. 9.47, Aen. 1.287, 8.681, and 6.790, a passage not cited by D.) that the games during which the comet appeared were in part funeral games for Caesar ( ludi funebres).5 Similarly, D. (p. 35) characterizes as erroneous the notice attributed to Baebius Macer (Serv. Auct. on Ecl. 9.47) that the comet appeared at the 8th hour.6 Regrettably, D. makes no effort to investigate the record of a comet observed by the Chinese in 44 so as to determine what link, if any, that sighting may have had to the Roman comet. He (p. 35) simply takes the statement that the Chinese saw a comet whose color was “reddish yellow” as possibly having some bearing on the implication in Calpurnius Siculus ( Ecl. 1.77-83) that Caesar’s Comet was red. D. does not think to ask why the comet observed by the Chinese in 44 had a reddish cast (an extremely rare attribute of a comet in the Chinese records, which does not turn up again until AD 178),7 nor does D. show any appreciation of the chronological problem posed by the Chinese sighting in May-June, as opposed to the sighting from Rome in July, if the two separate reports concern the same object.8

D.’s explanation for the change in the name of the festival during which the sidus Iulium appeared (the ludi Victoriae Caesaris, according to D., not the ludi Veneris Genetricis) and his explanation for the shift in the date of that festival from September to July suffer from relying upon old, discredited notions. D. (p. 31) is content to adopt to Mommsen’s theory that the 67 days added between Nov. and Dec. 46, as part of Caesar’s reform of the calendar, caused the new festival to Venus Genetrix to be celebrated two months earlier on its one-year anniversary in 45 and subsequent years: in July instead of September. D. also accepts Mommsen’s explanation for the renaming of the games, postulating that Venus Genetrix/Victrix was identical with “Victoria Caesaris”, a belief that can no longer be maintained in the light of more recent scholarship (see R-L 22-4). As Emma Gee pointed out in her review of D. ( CR 49.1999.177), the author shows no awareness of Stephan Weinstock’s Divus Julius (Oxford 1971), and so D. fails to appreciate the considerable difficulties in maintaining Mommsen’s position.9 D. is aware (p. 32 n. 11) that some scholars assign the sidus Iulium to September 44 instead of July, but he fails to realize the extent to which this view has represented the communis opinio among astronomers thanks to the auctoritas of Sir Edmund Halley, who mistakenly assigned Caesar’s Comet to September.10 In his treatment of the name and nature of the festival during which the comet appeared, D. tends to vacillate, minimizing on the one hand (p. 31) the number of sources (“alcune fonti”) that refer to the games by their old name ( ludi Veneris Genetricis), yet on the other hand explaining (p. 41) Caesar’s epithet “Dionaeus” in Ecl. 9.47 as an allusion to the ludi Veneri Genetrici [ sic ]. D. clearly fails to appreciate the significant fact, made clear by R-L in Appendix I (158-65), that not a single Greco-Roman source attesting the comet calls the games by the name ” ludi Victoriae Caesaris“. The predominance of the name ludi Veneris Genetricis for the games in 44 presents a considerable stumbling block for any theory of the sort put forward by Mommsen (endorsed by D.) or Weinstock, both of whom take it for granted that there was a celebration of the ludi Victoriae Caesaris in July 45, and subsequent years, in place of the festival to Venus Genetrix, which was held supposedly just once by Caesar in September 46.

D. had already concluded in 1989, and now in 1996 argues at greater length, that Caesar’s Comet experienced westward motion. Although there is some very slight evidence that the comet may indeed have been observed to move from east to west in the late spring/early summer months,11 the texts that D. employs to demonstrate movement in July simply do not stand up to scrutiny. The first of these texts is Dio 45.7.1, which states that the comet “appeared” ( ἐξεφάνη) ἐκ τῆς ἄρκτου πρὸς ἑσπέραν. D. interprets this notice as indicating that the comet moved from north to west, and in support of this meaning for πρὸς ἑσπέραν (which D. admits could signify “towards evening”, the meaning adopted by R-L 161), D. (p. 36) asserts that whenever Dio states the direction in which a comet or like phenomenon appears, he invariably (with one exception, 37.25.2) gives the direction of its motion. D. (p. 36 n. 33) lists nine passages in Dio as proof of his contention concerning Dio’s practice (37.25.2; 39.20.1; 40.47.2; 41.14.3; 45.17.4; 50.8.2; 54.19.7; 56.24.4; 78.30.1, a slip for 79.30.1). The trouble is, four of these passages (39.20.1; 40.47.2; 41.14.3; 56.24.4), despite the ambiguity of the term λαμπάς, clearly concern meteors, not comets, and so it is not surprising that Dio states the direction of the object’s movement. A fifth passage (37.25.2: noted by D. as the one apparent exception to Dio’s practice) most likely describes the Northern Lights, not a comet or a meteor. Of the remaining four passages that most probably do concern comets, D. fails to appreciate the fact that one of them (Dio 45.17.4) may add to our knowledge of the comet of 44 by describing how it appeared a month or two before it became daylight visible in July, and he completely misinterprets Dio 79.30.1, where Dio describes not movement of a comet but the direction of its tail.

There are two further serious obstacles to D.’s interpretation of πρὸς ἑσπέραν as “towards the west” in Dio’s description of the sidus Iulium : (1) Whereas in describing the comet of 44, Dio (45.7.1) employs the static verb ἐξεφάνη (“appeared”), in the nine passages cited by D. in which Dio reports the motion of a heavenly body, the author always uses verbs of motion ( ἀνατρέχω) twice; διατρέχω twice; φέρω twice; and ὁρμάω, διαίσσω, and ἀνατείνω once each). (2) Wherever Dio states that an object moved “to (or from) the west”, he writes πρὸς δυσμάς ( ἀπο τῶν δυσμῶν) — 37.25.2; 41.14.3; 45.17.4; 78.30.1 — not πρὸς ἑσπέραν (or ἀπὸ ἑσπέρας), which we find in the description of the comet of 44. Best to take πρὸς ἑσπέραν as an obvious allusion to the unusual feature of Caesar’s Comet that it was daylight visible, a fact reported by Octavian in his Memoirs and three other sources (Sen. Q Nat. 7.17.2; Suet. Iul. 88; Obseq. 68), which clearly drew either directly or indirectly upon Octavian’s account.12 The second text that D. cites to bolster his interpretation of Dio’s πρὸς ἑσπέραν as “towards the west” is a fragment commonly assigned to Avien(i)us13 (ap. Serv. Auct. ad Aen. 10.272), which purports to describe a propitious comet that appeared “when Augustus come to power” ( eo tempore quo est Augustus sortitus imperium). This Latin text, however, pace D., gives no indication of the comet’s movement. It may be that D. has been misled by the French translation of Jean Soubiran (Paris: Budé, 1981, p. 298), whose edition D. cites on several occasions (see D.’s “Indice degli studiosi”, p. 183). The key phrases in Avien(i)us are si orientem attenderit, which Soubiran renders “si elle se dirige vers orient” and si occidentem inspexerit, which Soubiran renders “si elle regarde l’occident”. Clearly attendere in this passage = spectare ( TLL 2.5.1122.83ff), and the author uses both attendere and inspicio to indicate the position of the heavenly body, not its motion.14

In both the earlier monograph (1989) and in this revised and expanded study (1996), D. tries very hard to extract from Virgil’s allusion to Caesar’s Comet in Eclogue 9 precious information about its position in the heavens. D. seeks to find an acrostic in vss. 43-51 of Ecl. 9, picking out the first letter of every other verse to spell HAEDO, which D. interprets as a cryptic reference to the asterism known as the Haedi (“Kids”) in the constellation Auriga ( ε η and ζ AUR).15 As D. himself shows (Figs. 1a, 1b, and 1c, pp. 44-6), however, the Haedi were in the wrong place at the wrong time to make a very satisfactory location for Caesar’s Comet, which we are told rose during the eleventh hour (= approx. 17:00-18:15 LMT, Rome). The Haedi, by contrast, did not begin to rise until two and a half hours after sunset,16 and when they did appear above the NE horizon, they would have been east of all five hypothetical locations of the comet marked by D. on his figures. Hence their location is at odds with D.’s assumption that the comet experienced westward motion. Furthermore, in order to produce his acrostic, D. must make two very odd breaks in Virgil’s text by including vss 43 and 51 (yielding the “H” and “O” respectively of “HAEDO”) with vss. 44-50, which form a single unit of Lycidas’ song (so Mynors (Oxford 1969), while Coleman (Cambridge 1977) assigns vss. 44-5 to Moeris). At best, vss 43 and 51 can be viewed as providing a “frame” for words spoken by Lycidas, but there can be no rationale for treating vss. 43-51 as a unit.

In support of his view that HAEDO is to be regarded as an intentional acrostic on Virgil’s part, D. draws attention to the direct mention of the asterism “Haedi” in Theocritus 7.52, where the homonymous Lycidas begins his song. Might not that circumstance, however, lead to a different conclusion? Viz., if Virgil consciously embedded the letters (ἠαεδ) in the verses sung by Lycidas in celebration of Caesar’s Comet, his intent could have been simply to produce a learned allusion to Theocritus, and consequently that asterism has no connection whatsoever with the sidus Iulium. One could just as well argue, I suppose, if one is in a fanciful mood, that Virgil intended the acrostic HAEDO to echo the prior and subsequent references in Ecl. 9 to the “kids” ( haedi) that Moeris was forced to turn over to a new master ( Ecl. 9.7 and 63). Finally, as D. himself has to admit (p. 51), if in Lycidas’ song Virgil intentionally alluded to the Haedi as an example of stars that formerly guided men’s activities by their time of rising ( quid antiquos signorum suspicis ortus ?) but now surrender that function to “Caesar’s star” ( Caesaris astrum), the Haedi make a poor choice for comparison with a comet in July because the Kids are closely associated with the advent of stormy weather in autumn.

In addressing the many complex problems posed by the interpretation of the sidus Iulium (e.g., how a comet, invariably a baleful omen, came to be regarded as a favorable sign, or how a comet, given the relatively short span of its visibility, could serve as a symbol for Caesar’s catasterism), D. overlooks what appears to have been a lively contemporary debate over the nature of the celestial phenomenon. That is, our ancient sources make it abundantly clear that whereas some eyewitnesses claimed that the object in the sky was a “new star” (not a comet), others just as vehemently asserted that the heavenly body was a baleful comet (see R-L 139-45). This sharp division in opinion is reflected in the treatment of the sidus Iulium in our literary sources (“star” as good omen, “comet” as omen of renewed civil war). D. shows no awareness that the ancient sources point to this disagreement among contemporary observers, and yet the author himself subconsciously(?) vacillates in his terminology, at times referring to the sidus Iulium as “un nuovo astro” (p. 62) and at times as a “cometa” plain and simple (p. 64).

To add a few sundry, brief observations: Pace D., the Temple of Divus Iulius was not“in Foro di Cesare” (p. 62). D. misses an opportunity to discuss the possible bearing that the planet Venus could have had on the interpretation of Caesar’s Comet (see R-L 138), because he mistakenly states that Venus set at approx. 18:00 on 20 July 44 BC (p. 64 n. 98), whereas in fact it must have been visible in the western sky for almost an hour after evening twilight.17 D. (p. 76 n. 136) commits a common error in stating that there was a comet in 43 BC that presaged the death of Cicero.18 The comet in question (Dio 45.17.4) was none other than the sidus Iulium of 44 BC 92)! Pace D. (79), the comet reported by Seneca ( Q Nat. 7.15.2) is not itself credited with being “fausto”, nor did it appear in 137 BC. Rather, it is most likely identical with the first of the two comets associated with Mithridates VI that were treated as auspicious; and it should be assigned to 135.19 D. tries to explain what he views as the waning importance of the sidus Iulium in the last decade BC as resulting from the declining stature of Julius Caesar under the Augustan regime (pp. 60-1). This interpretation, however, sweeps under the carpet Ovid’s celebration of the sidus Iulium in his Metamorphoses, which was written in the last decade BC. Furthermore, any argument of the sort advanced by D. needs to take into account the important paper of Peter White on the way Julius Caesar was portrayed in Augustan literature ( Phoenix 42 (1988) 345-53), a work of which D. shows no awareness. Interestingly, both D. (119-20) and R-L (147-53) independently arrive at similar conclusions concerning how the position of the constellation Capricorn (on the eastern horizon at the time of the comet’s rising) may explain Augustus’ cryptic words (reported by Pliny, NH 2.94) that “the comet had come into being for him and that he was coming into being in it” ( sibi illum [sc. cometen ] natum seque in eo nasci). D. makes a valiant attempt to shed further light on the possible location of the “ghost” constellation Caesaris Thronus and its possible connection with the sidus Iulium, but that will-o’-the-wisp defies all attempts to pin it down. It is best left to one side (R-L 86 n. 65).

To sum up, this book sets out to show how the sidus Iulium and the apotheosis of Caesar prepared the way for the significant role played by astrology and the stars in the lives of the Roman emperors during the first century AD. The foundation on which D. builds, however, is shaky because he does not always make the best use of the ancient sources, and he is furthermore unaware of many important pieces of anglophone scholarship. There is a vast body of evidence for the sidus Iulium that D. scarcely taps, and there are many questions to be put to this evidence which D. passes over in silence. Unfortunately these same shortcomings are also present in other parts of the monograph, and so I can only recommend that this work be consulted with caution.


1. Despite the “out-of-print” notice for this title at “”, the publisher informs me that this book is in-print, at the price stated.

2. Only seven US libraries are listed in the OCLC “World Catalogue” on-line record for this title.

3. The Comet of 44 BC and Caesar’s Funeral Games (Atlanta: Scholars Press, 1997).

4. Weinstock, Divus Julius 378-9, the reference to the comet in Carm. 1.12.46 being, at most, indirect (Nisbet-Hubbard ad loc. pp. 162-3).

5. See R-L 48-50 for a discussion of this evidence and how it may be supported by Gaius Matius’ reference to the “duty” ( munus) he felt himself obliged to shoulder in providing financial backing for Octavian’s celebration of the games in 44 ([Cic.] Fam. 11.28.6).

6. For a possible explanation of this significant departure from Octavian’s assertion that the comet appeared during the 11th hour, see R-L 130.

7. For the conclusions about atmospheric conditions that can be drawn from this color, see R-L 106, and see R-L 99-107 on the considerable body of evidence pointing to the presence of a volcanic veil in the spring of 44.

8. For a discussion of the accuracy of Chinese astronomical records and the state of the Chinese calendar in 44 BC (-43), see R-L 65-8; on the troubling silence of our sources (Greco-Roman for May-June, Chinese for July), see R-L 95-107 and 107-12 respectively; and for the probability that the two sightings concern the same comet, see R-L 116-7.

9. See R-L 41-7 for a demonstration that the games were most likely moved (but not renamed) by Octavian in 44, not by Caesar in 45 as scholars have generally assumed. There is only one text pointing to a possible celebration of the ludi Victoriae Caesaris in July 45 ( Att. 13.44.1), and R-L 25-40 have shown that that text alludes not to the new festival founded by Caesar but to the ludi Apollinares (6-13 July), a conclusion accepted by Shackleton Bailey in his new edition of the Letters to Atticus (Loeb vol. 4, 103 n. 1: Cambridge, MA, 1997).

10. See R-L 3 n. 9 for a collection of these weighty authorities. Gary Kronk, writing for astronomers in Cometography vol. 1 (Cambridge 1999) 22-3, now follows R-L in assigning the sidus Iulium to July 44 (a date taken for granted by most classical scholars), and so it is to be hoped that astronomers will henceforth adopt this date as well.

11. Dio 45.17.4; Obseq. 68 fax caelo ad occidentem visa ferri : see R-L 91-4 for a discussion of this evidence.

12. See Appendix V in R-L (189) for a tabular summary of the parallels between our later sources and Octavian’s account of the comet in his Memoirs.

13. See now, however, P. Keyser, Mnemosyne 47 (1994) 641-4, for a convincing demonstration that the attribution to Avien(i)us should not be taken for granted.

14. This can be demonstrated (1) by comparing the use of the synonym respexerit earlier in the same passage of Avien(i)us with respexerit in Firmicus ( Mathesis 7.23.1) where Firmicus gives the position of Saturn in quartile aspect with the sun, and (2) by treating the Greek text of John Lydus as a gloss on si occidentem inspexerit (both Avien(i)us and Lydus going back to a common source: parallel texts conveniently laid our by Riess, Philologus, suppl. vol. 6.1, 1892, p. 350): εἰ δὲἐπὶ τὴν δύσιν ὁρᾷ.

15. D. first argued for this interpretation in a conference paper published in L’ astronomia a Roma nell’ età augustea (1989) 91-106: “I ‘Capretti’ de Virgilio. Note sui catasterismo di Giulio Cesare”.

16. On 20 July 44, sunset at Rome was at 19:30 MLT, and ε η and ζ AUR rose at 21:59, 22:23, and 22:22 respectively (calculations made by means of “SkyClock”, an electronic ephemeris and calendar-conversion program, copyrighted by the late Pierre Brind’Amour).

17. According to “SkyClock” (see above, n. 16), Venus set on 20 July 44 BC at 20:54 MLT Rome. In his 1989 publication, D. states that his astronomical calculations were made by employing a software program written by P. Massimino, but I find no comparable source given in the 1996 book.

18. So too Gundel, “Kometen”, RE 11.1 (1921) 1187; cf. A.A. Barrett, Jour. of the Royal Astron. Soc. of Canada 72 (1978) 96.

19. See J.T. Ramsey, HSCP 99 (1999) 220-2.