Caer Australis - Celtic Calendar: Pleiades Cycle

"Who can tell the Phases of the Moon?" - Song of Amergin

The Pleiades Cycle

samon duman rivros anagantios ogronnos cvtios || giammon semivisonna equos elemivios aedrini cantlos

The distinctive star cluster within the constellation of Taurus has long served humankind as the signal for the turn of the seasons. Their ancient rise in May signalled the coming warmth of summer; their setting the cold of winter. Of far greater utility than the solsticial extremes of the sun in deep winter or high summer, the Pleiades provided the signals for the seasonal transitions and the timing of agricultural practices vital to the well-being of communities. The cluster appears in mythologies from around the world (for a review see Pleiade.org's 'The Pleiades in mythology') and presented here are reports from the ancient sources relating to the Pleiades and the Celtic calendar system.

The Pleiades May Rising

By the time of the rise of the Celtic culture as a distinct member of the Indo-European family, typically dated to the eighth century BC with the Hallstatt archaeological period, the Pleiades had been long recognised for their significance. From the Bronze age of Europe has been discovered a bronze device, the 'Nebra Star Disc', dated to 1600BC, featuring the Sun, Moon and Pleiades (see: Landesmuseum für Vorgeschichte website). The Greek poet Hesiod wrote of their astronomical signposting in the eighth century BC as the iron age reached Europe (Hesiod, Works and Days, 380). The Celts of Britain and Gaul marked a thirty year celestial cycle completed when Saturn returned to the sign of Taurus (Plutarch, De Facie, Loeb p.185) marking an 'age' in their calendar system, as recorded by Pliny the Elder in the first century AD (Natural History, 17.95). The rise of the Pleiades also marked the completion of a lunar festival in Britain, as the moon completed a nineteen year Metonic cycle (Diodorus, Library of History 2,47).

The rising of the Pleiades occurs when their celestial appearance over the eastern horizon co-incides with the rising of the sun. In the first millennium BC, this occurred in May, though today they rise in June. The May rise of the Pleiades and Taurus is co-incident with the Celtic festival for the start of summer, Beltaine. When the Roman calendar was introduced into Ireland in the fifth century AD, the month of May was rendered as Cétemain, from cet-Samhin, 'the first of summer' (McBain, 1982), maintaining the ancient beginning of summer in the Celtic world.

In 503BC a spectacular Pleiades rising was visible across Europe, with Saturn rising in Taurus, accompanied by Jupiter, Venus and Mercury, and with Mars close by in Aries. Co-incident with the start of a Celtic thirty year cycle, this planetary alignment brought all the visible planets together on the eastern horizon. It was about 500BC that the Celtic La Tène archaeological period opened, the flourish of Celtic culture.

The Nebra Star Disc

The Pleiades were recorded in Bronze age Europe as a cluster of stars on the 'Nebra Star Disk', dating to around 1600BC and produced from metals found in Europe (Secrets of the Star Disc, 2004). The disc combines images of the Sun and Moon, an arc delineating the angle on the horizon produced between solsticial extremes, and a star-field in which appear a distinctive cluster of seven stars, the Pleiades. The disc is presently exhibited at the Landesmuseum für Vorgeschichte in Halle, Germany, described as "an in-depth view of the astronomical knowledge" of pre-historic Europeans (Landesmuseum website).

Hesiod's 'Works and Days'

The poet Hesiod wrote in the eighth century BC an epic poem describing the passage of the year and the tasks to perform during its course. Within its lines, the Pleiades are mentioned as markers of the seasons: "[380] More hands mean more work and more increase. If your heart within you desires wealth, do these things and work with work upon work. When the Pleiades, daughters of Atlas, are rising, [in May] begin your harvest, and your ploughing when they are going to set [in November]. [385] Forty nights and days they are hidden and appear again as the year moves round, when first you sharpen your sickle. This is the law of the plains, and of those who live near the sea, [390] and who inhabit rich country, the glens and hollows far from the tossing sea: strip to sow and strip to plough and strip to reap, if you wish to get in all Demeter's fruits in due season, and that each kind may grow in its season" (Hesiod, Works and Days, 380).

Celebration of the Hyperboreans

Diodorus Siculus, who lived from 80-20BC, was a Greek historian of Agyrium in Sicily who wrote forty books of world history, called Library of History. He relates, "facing the land of the Celts in the parts of the Ocean, there is an island, which is not smaller than Sicily, situated in the northern region and inhabited by the Hyperboreans, who are called by that name because their home is beyond the point whence the north wind [Boreas] blows" (Diodorus, Library of History 2,47).

The Hyperborean priests are reported by Diodorus to a hold a luni-solar festival complete at the rising of the Pleiades every nineteen year 'Metonic' cycle. Meton, the fifth century BC Greek astronomer, discovered that every 235 lunations, equal to nineteen solar years, the full moon occurs on the same calendar date.

He relates, "The account is also given that the god [Apollo] visits the island every nineteen years, the period in which the return of the stars to the same place in the heavens is accomplished; and for this reason...is called by the Greeks the 'year of Meton'. At the time of this appearance of the god he both plays on the cithara and danced continuously the night through from the vernal equinox until the rising of the Pleiades, expressing in this manner his delight in his successes" (Diodorus, Library of History 2,47).

The Thirty Years of Cronus

Plutarch's dialogue 'The Face in the Moon' was inspired by a total solar eclipse observed in the Mediterranean, probably that of AD75. Here, an account is given of Cronus, father of Zeus, entrapped on an island in the Ocean westward of Britain, "Cronus himself sleeps confined in a deep cave of rock that shines like gold - the sleep that Zeus has contrived like a bond for him" (Plutarch, De Facie, Loeb p.187).

The myth of Cronus may have been suggested to Plutarch by Demetrius of Tarsus, who is said in the dialogue to have recently returned from Britain, and he may be relating a Celtic legend that was suitably Hellenized by Plutarch for his audience (De Facie, Loeb Introduction). The information was obtained after the Claudian invasion of Britain in AD43; not long before the composition of this dialogue, the Druidic groves on the island of Môn had (in AD61) been attacked.

In Plutarch's account are reflections of a comment made by Caesar in 54BC, who wrote, "The interior portion of Britain is inhabited by those of whom they say that it is handed down by tradition that they were born in the island itself: the maritime portion by those who had passed over from the country of the Belgae for the purpose of plunder and making war; almost all of whom are called by the names of those states from which being sprung they went thither" (Caesar, Bellum Gallium, 6.18). Plutarch's relates, "These people consider and call themselves continentals and the inhabitants of this land islanders because the sea flows around it on all sides" (Plutarch, De Facie, Loeb p.183).

Similarities to the Irish Book of Invasions are seen in Plutarch's account, "they believe that with the peoples of Cronus there mingled at a later time those who arrived in the train of Heracles [who] rekindled again to a strong, high flame the Hellenic spark there which was already being quenched and overcome by the tongue, the laws, and the manners of the barbarians. Therefore Heracles has the highest honours and Cronos the second" (Plutarch, De Facie, Loeb p.185).

With respect to Celtic time-keeping, Plutarch relates, "Now when at intervals of thirty years the star of Cronus, which we call 'Splendent' but they, our author said, call 'Night-watchman', enters the sign of the Bull, they, having spent a long time in preparation for the sacrifice and the expedition, choose by lot and send forth a sufficient number of envoys in a correspondingly sufficient number of ships ... while those who have served the god together for the stint of thirty years are allowed to sail off home" (Plutarch, De Facie, Loeb p.185).

Pliny the Elder

The thirty year circuit of Saturn is presented in Pliny the Elder's discourse of the planets and their attributes: "It is certain that the star called Saturn is the highest, and therefore appears the smallest, that he passes through the largest circuit, and that he is ac trigesimo anno ad brevissima sedis suae principia regredi at least thirty years in completing it" (Pliny, Natural History, 2.6). This section 'Of The Nature Of The Stars; Of The Motion Of The Planets', published in AD77 is an invaluable resource as an insight into ancient perceptions of the universe.

Thirty years is the period Pliny assigns as the largest unit of Celtic time-keeping. He tells us that for the Druids of Gaul, "the fifth day of the moon [is] the day which is the beginning of their months and years, as also of their ages, which, with them, are but thirty years. This day they select because the moon, though not yet in the middle of her course, has already considerable power and influence; and they call Her by a name which signifies, in their language omnia sanantem the all-healing" (Pliny, Natural History, 17.95).

Pliny, who composed his encyclopaedic work in the period following AD52 until his death in AD79 whilst studying the eruption of Mt Vesuvius, positively identifies the thirty year period as part of the Celtic calendrical system. That the Celts used the first-quarter moon as the first day of their months explains why their period of the day extends from successive sunsets: on the first day of the Celtic month the moon is directly overhead split into dual sunlit and dark halves, a precise astronomical observation.

Caesar a century earlier (53BC) reported the sunset beginning to the Celtic daily period: "they compute the divisions of every season, not by the number of days, but of nights; they keep birthdays and the beginnings of months and years in such an order that the day follows the night" (Caesar, Bellum Gallium, 6.18).

The Celtic Calendar System and the Pleiades

From their Bronze age forebears through to the times of Roman conquest, the Celts across the sweep of northwest Europe and the islands of the Ocean are shown by the ancient historians to have keenly marked the Pleiades in their religious astronomical observations and festivals. The rise of the Pleiades and the constellation of Taurus in May marked the thirty year age, as the planet Saturn completed its circuit of the heavens. The most recent conjunction of Saturn in Taurus was in AD2002, when a major conjuction of the planets was visible first at sunset in April and later in May and June at their heliacal rising on the dawn horizon (Harvard University Gazette, 2000; see also: a screenshot of the heliacal rise of the Pleiades and Saturn in 2002 on the introductory page for the Celtic Calendar 2008 and Saturn Return 2002).

We are not limited only to the ancient sources for our knowledge of the Celtic calendar system. From the time of Caesar's conquest of Gaul has survived a bronze inscription, called the 'Coligny Calendar' or the 'Gaulish Calendar', detailing the months and years of the Celtic calendar. To this we now turn in the following section, armed with the knowledge recorded by the historians contemporary with its use.

References for this section.

ancient sources

C. Julius Caesar. Caesar's Gallic War. Translator. W. A. McDevitte. Translator. W. S. Bohn. 1st Edition. New York. Harper & Brothers. 1869. Harper's New Classical Library. [available on-line:
http://www.perseus.tufts.edu/cgi-bin/ptext?lookup=Caes.+Gal.+6.18 ]

Diodorus, Library of History Book II, Loeb translation, In: Hawkins, G. (1965) Stonehenge Decoded. Fontana, London, pp.165-166.

Hesiod. The Homeric Hymns and Homerica with an English Translation by Hugh G. Evelyn-White. Works and Days. Cambridge, MA., Harvard University Press; London, William Heinemann Ltd. 1914. [available on-line:
http://www.perseus.tufts.edu/cgi-bin/ptext?lookup=Hes.+WD+1 ]

Pliny the Elder. The Natural History. John Bostock, M.D., F.R.S. H.T. Riley, Esq., B.A. London. Taylor and Francis, Red Lion Court, Fleet Street. 1855. [available on-line:
'Of The Nature Of The Stars; Of The Motion Of The Planets': http://www.perseus.tufts.edu/cgi-bin/ptext?lookup=Plin.+Nat.+2.6]
'Historical Facts Connected With The Mistletoe': http://www.perseus.tufts.edu/cgi-bin/ptext?lookup=Plin.+Nat.+17.95]

Plutarch. Moralia. De Facie 'The Face in the Moon' with an introduction. Vol. XII of the Loeb Classical Library edition, 1957. [available on-line:
http://penelope.uchicago.edu/Thayer/E/Roman/Texts/Plutarch/
Moralia/The_Face_in_the_Moon*/Introduction.html ]

websites and image credits

'Breathtaking Saturn' image: http://science.nasa.gov/headlines/y2002/13dec_saturn.htm

CyberSky - Astronomy Software for Windows. http://www.cybersky.com/
Dawn screenshot image: Latitude - London co-ordinates, May 503BC

Harvard University Gazette, April 18 2002: Cromie, W. 'All planets will be visible for once-in-a-lifetime sight': http://www.hno.harvard.edu/gazette/2002/04.18/01-planets.html

Landesmuseum für Vorgeschichte in Halle, Germany; 'Nebra Star Disc' image. http://www.archlsa.de/sterne/

'Lascaux depiction of bull from 15,000BC' image: http://home.netcom.com/~abraxas2/zodiac.htm

'Pleiades star cluster' image: http://apod.nasa.gov/apod/ap031227.html

Secrets of the Star Disc, Transcript of BBC2 presentation, 2004. http://www.bbc.co.uk/science/horizon/2004/stardisctrans.shtml

'Taurus' image: http://domeofthesky.com/clicks/tau.html

The Pleiades in mythology. http://www.pleiade.org/pleiades_02.html