Cairnpapple — Neolithic Solar Calendar

Cairnpapple Today (Mon, 30th Mar 2015)
Sunrise:6:52 am (BST) @ 82.3
Sunset:7:48 pm (BST) @ 278.2

Anawr gynhoruan huan arwyran ·
gwledic gwd gyfgein nef enys brydein ·

Llyfr Aneirin 5.7–5.8

G F E D C B A

Cove & Pit-Arc Sunrise Alignments in 2015

2015 Sunrise Events
EventDateUTCLocalAzimuthPitKey
Quarter Day 1 (Imbolc)February 3rd08:068:06 am119.2B
Semiquarter Day 1February 25th07:177:17 am105.3C
Spring EquinoxMarch 20th06:186:18 am89.3D
TodayMarch 30th05:526:52 am82.3
Semiquarter Day 2April 12th05:186:18 am73.4E
Quarter Day 2 (Bealltainn)May 5th04:235:23 am58.8F
Summer SolsticeJune 21st03:294:29 am43.2G
Quarter Day 3 (Lùnasdal)August 7th04:305:30 am58.2F
Semiquarter Day 3August 30th05:156:15 am72.5E
Autumn EquinoxSeptember 23rd06:017:01 am88.7D
Semiquarter Day 4October 15th06:457:45 am103.9C
Quarter Day 4 (Samhuinn)November 7th07:347:34 am118.7B
Winter SolsticeDecember 22nd08:448:44 am133.5A

In his excavation report on Cairnpapple, Stuart Piggott identified the site’s earliest Neolithic structures as: (1) an “irregular arc” of 7 stone-holes (A–G) cut into the basalt bedrock and (B–G) containing traces of cremation deposits; (2) an east-facing “cove” of 3 further stone-holes (PSAS 82 68–123). Piggott himself did not directly connect these two structures, nor did he suggest any calendrical function for them. However, such seems compelling when we map onto his excavation plan the sunrise azimuths for solstices (pits A & G), equinoxes (pit D) and quarter-days (pits B & F), with 4 additional dates apparently indicated exactly halfway between equinoxes and quarter-days (pits C & E) which I’m provisionally calling “semiquarter days” until I can think of something better. Whence this webpage, under development (particularly its maths) towards being a dynamically-programmed representation of Cairnpapple’s “Neolithic Solar Calendar”. If you’ve got any useful feedback, I’d be glad to hear from you.

Astronomical data calculated using NASA’s JPL HORIZONS ephemeris tool. Times & azimuths are topocentric refracted estimates for the centre of the solar disk on (currently) a notionally level horizon.
View maps at OS Magic or Google. Visit the non-virtual Cairnpapple with Historic Scotland. Consult the local weather oracle at the Met Office. Find illumination in Llyfr Aneirin at The National Library of Wales.