The Crossover of the Sun and the Moon

For Stonehenge and Avebury see, for instance, Ruggles Clive , Astronomy in prehistoric Britain and Ireland (New Haven and London, 1999), 12–19, 35–41, 136–9. For Malta see Cox John Lomsdalen Tore , “Observations of moonrise and sunrise from ancient temples in Malta and Gozo”, Journal of cosmology , ix (2010), 2217–31.

Ruggles , op. cit. (ref. 1), 91–111.

See, for instance, Gullberg Steven R. , “Inca solar orientations in southeastern Peru”, Journal of cosmology, ix (2010), 2078–91.

See, for instance: Fabian Stephen M. , Space-time of the Bororo of Brazil (Florida, 1992); and MacDonald John , The arctic sky: Inuit astronomy, star lore and legend (Ontario, 1998).

da Silva Cândido Marciano , “The spring full moon”, Journal for the history of astronomy, xxxv (2004), 475–8.

Pimenta Fernando Tirapicos Luis , “The orientations of central Alentejo megalithic enclosures”, in Astronomy and cosmology in folk traditions and cultural heritage (Archaeologia Baltica 10, 2008), 234–40, and Pimenta Fernando Tirapicos Luis Smith Andrew , “A Bayesian approach to the orientations of central Alentejo megalithic enclosures”, Archaeoastronomy , xxii (2009), 1–20.

Silva Fabio , “Equinoctial full moon models and non-Gaussianity: Portuguese dolmens as a test case”, in Rappengluck Michael Rappengluck Barbara Campion Nicholas (eds), Astronomy and power (British Archaeological Reports, in preparation).

da Silva , op. cit. (ref. 5).

Silva , op. cit. (ref. 7).

Ruggles Clive , “Whose equinox?”, Archaeoastronomy, no. 22 (supplement to Journal for the history of astronomy, xxviii (1997)), S45–96, and idem, op. cit. (ref. 1), 148–9.

See www.moshier.net.

The formulas for computation of ΔT and the table from the Astronomical almanac used for interpolation by Alcyone Software, along with a discussion of methods of determining ΔT, can be found online at http://www.phys.uu.nl/∼vgent/deltat/deltat.htm.

Caldwell John Laney C. David , “First visibility of the lunar crescent”, African skies, v (2001), 15–23.

Odeh Mohammad , New criterion for lunar crescent visibility (Islamic crescents' observation project (ICOP), 2006).

Yallop B. D. , “A method for predicting the first sighting of the new crescent moon”, NAO technical note, no. 69 (HM Nautical Almanac Office, Cambridge, 1998).

See Maunder M. , “On the smallest visible phase of moon”, Journal of the British Astronomical Association, xxi (1911), 355–62; Indian astronomical ephemeris (Indian Meteorology Department, New Delhi, 1979); and Bruin F. , “The first visibility of the lunar crescent”, Vistas in astronomy , xxi (1977), 331–58.

Schaefer Bradley E. , “Astronomy and the limits of vision”, Vistas in astronomy, xxxvi (1993), 311–61.

Schaeffer , op. cit. (ref. 17).

Schaefer Bradley E. , “Visibility of the lunar crescent”, Quarterly journal of the Royal Astronomical Society, xxix (1988), 511–23.

Silva , op. cit. (ref. 7).

See García C. Gonzalez Ferrer L. Costa Belmonte L. Antonio Belmonte J. Antonio , “Solarists vs. lunatics: Modelling patterns in megalithic astronomy”, in Zedda M. Belmonte J. (eds), Lights and shadows in cultural astronomy (Isili, 2007), 23–30; and González C. Belmonte J. , “Statistical analysis of megalithic tomb orientations in the Iberian Peninsula and neighbouring regions”, Journal for the history of astronomy , xxxi (2010), 225–38.

The time-span distribution between the two equinoctial crossovers shows that most of the times 6 synodic months separate the two events, although an additional 7th month is also common (around 38% of the time). This suggests that the equinoctial crossover events could have been usefully used to regulate a seasonal calendar, composed of 2 periods, of roughly six or seven months each, yielding a year of 12 or 13 lunations synchronized to the EFMs. The modern Hebrew calendar is currently synchronized to this crossover, the first day of Passover (the 15th of the month of Nisan) always occurring on the eve of the spring full moon. This calendar is based around the 19-year Metonic cycle in which there are 7 leap years of 13 lunations (i.e. 37% of the cycle). A full analysis of this calendar, in both its modern and ancient forms, to verify whether it is always synchronized with the one given by the equinoctial crossovers, is needed to confirm this.

Laskar J. , “Secular terms of classical planetary theories using the results of general theory”, Astronomy and astrophysics, clvii (1986), 59–70.

Pimenta Tirapicos Smith , op. cit. (ref. 6) and Silva, op. cit. (ref. 7).

Available online at: http://ssd.jpl.nasa.gov/?horizons.

Espenak Frank Meeus Jean , Five millennium canon of solar eclipses: −1999 to +3000 (2000 BCE to 3000 CE) (2006), available online at: http://eclipse.gsfc.nasa.gov/SEcat5/deltatpoly.html.

da Silva , op. cit. (ref. 5), Silva, op. cit. (ref. 7), and Gonzalez Belmonte , op. cit. (ref. 21).

Silva , op. cit. (ref. 7), and Schaefer B. Liller W. , “Refraction near the horizon”, Publications of the Astronomical Society of the Pacific, cii (1990), 796–805.

Silva , op. cit. (ref. 7), and Silva Fabio , “Cosmology and the Neolithic: A new survey of Neolitihic dolmens in central Portugal”, Journal of cosmology, ix (2010), 2194–206.

Pimenta , Tirapicos and Smith, op. cit. (ref. 6).

Ruggles Clive , “Stone rows in south-west Ireland”, Archaeoastronomy, no. 21 (supplement to Journal for the history of astronomy, xxvii (1996)), S55–71; and idem, op. cit. (ref. 1), 102–11.

Silva , op. cit. (ref. 7), and Gonzalez Belmonte , op. cit. (ref. 21).

Lebeuf Arnold , “Le soleil nous porte ombrage”, in Zedda Belmonte (eds), op. cit. (ref. 21), 155–64.

See Sims Lionel , “The solarization of the moon: Manipulated knowledge at Stonehenge”, Cambridge archaeological journal, xvi (2006), 191–207; and Sims Lionel , “What is a lunar standstill? Problems of accuracy and validity in ‘The Thom paradigm’”, Mediterranean archaeology & archaeometry , special issue, vi (2007), 157–63.