The myth of Apollo leaving Delphi in his yearly travelling to Hyperborea for the three winter months  is well known. During this time, the god was said to be absent from Delphi and no consultations took place. Nonetheless, there might be more concrete elements to this story than first meets the eye: it might be linked to the night sky.

The constellations that are visible from Delphi in different times of the year might give us a clearer understanding of how important dates were determined. Three constellations seem to be of special importance here: Cygnus (the swan), Lyra (the lyre) and Delphinus (the dolphin). As one can see, those constellations are all very closely together.

Before we get into details as to how those constellations might have played a role in determining oracular dates, it´s worth mentioning that all of them are strongly related to Apollo. The lyre is one of  Apollo's most important symbols, this goes without saying. Also his transformation into a dolphin plays an important role in the founding of his Delphic oracle, according to the Homeric Hymn to Apollo:

[...] but they were encountered by Phoibos Apollo;

down on the sea he suddenly leapt, in his shape like a dolphin,

on the swift galley, and lay there, a monster enormous and fearful;

Swans are also strongly associated with him and with Hyperborea. Take, for example, Callimachus' Hymn to Delos:

...and with music the swans the gods’ own minstrels, left Maeonian Pactolus and circled seven times round Delos, and sang over the bed of child-birth, the Muses’ birds, most musical of all birds that fly.

Additionally, lyric poet Alcaeus tells us:

When Apollo was born, Zeus equipped him with golden headband and lyre and gave him also a chariot of swans to drive, and sent him to Delphi and the spring of Castalia, thence to declare justice and right for the Greeks; but when Apollo mounted the chariot he directed the swans to fly to the land of the Hyperboreans. Now when the Delphians learned this, they composed a paean and a tune and arranged dancing choirs of youths around the tripod and called on the god to come from the Hyperboreans.

It´s not hard to find imagery of Apollo associated with lyres, swans, sometimes dolphins, or even all of them at once:

The imagery is very intertwined, which makes a lot of sense if the idea of an astronomical background is true. 

Oracular Dates

During its early days, oracular activity took place only once a year, in the seventh day of the Delphic month of Bysos, likely equivalent to the Attic month Anthesterion, which in modern calendars might fall roughly in February/March. With time, this practice gave place to consultations once a month, always on the seventh day, according to the standard lunar calendar calculations. This was not all year round, however: as previously stated, there was no activity in the winter months, when the sanctuary.

How exactly might that be linked to the constellations above?

The landscape of Delphi is covered by mountains, which in many ways restricts the view of the sky. Interestingly, taking the Temple of Apollo as the point of reference for observation, the three constellations seem to vanish and return (in fact not being visible behind the rocky Faidriades) in a way that seems to align really well with the Hyperborean narrative: During January, February and March, it was not possible to observe them at their zenith, from Delphi. Around the 7th of Bysos, they reappear from the first time, and would only be absent again with the subsequent winter.

The geographical characteristics of Delphi also meant that it was likely that other locations in Greece could observe the changes in the stars and calculate the dates in which oracles would take place with enough anticipation so as to organize the travel all the way to Delphi. Heliacal rising of the constellation Delphinus would be visible two weeks earlier in a flat horizon, when compared to Delphi.

This was especially important in older times when the oracle was a once a year event, but, given the Panhellenic nature of the site and the localised calendars that were so common in Ancient Greece, the use of astronomical cues seems like a feasible and reliable solution.

This post was mostly informational but I do believe it holds interesting ideas that might inspire reconstructionists, Delphic or otherwise (upcoming 7th of Bysos I´m looking at you!)

Further reading:

Efrosyni Boutsikas. Landscape and the Cosmos in the Apolline Rites of Delphi, Delos and Eros. In: L Käppel and V Pothou. Human Development in Sacred Landscapes. 2015