# Sun, Moon and Earth

39 38 the 19 year metonIc cycle the marriage of Sun and Moon After 19 years, and within two hours of exactitude, the Sun and Moon return to the same places in the sky on the same date. This astonishly accurate repeat cycle is named after Meton, a 4th century BC Greek astronomer. It does not involve the Moons nodes and therefore does not produce eclipses. Another similar and important cycle takes 8 years, or 99 lunations and is synchronised with the 5 synods of Venus, the famous Venus pentagram Aveburys outer ring once comprised 99 stones. The 1st century BC historian Diodorus suggested that the Celts knew of the 19 year cycle. We need not be surprised at his account, for the Celts inherited the culture of the stone circle builders, and many fine circles, particularly in southwestern Britain, contain 19 stones Boscawenun in Cornwall shown opposite. The bluestone horseshoe at Stonehenge comprised 19 slender polished megaliths, brought from the Preseli mountains of West Wales, 135 miles as the crow flies. Some weighed over four tons There are 12.368 lunations full moons in one solar year. The lunar year of 354.367 days 12 lunations falls short of the solar year by just under 11 days, which after 19 years accrues to 7 lunations, totalling 12 x 19 plus 7, or 235 lunations. From these numbers, the annual number of lunations may be found 235 19 equals 12 , or 12.368, the fraction better revealing the underpinning astronomy. 19 solar years is 6939.60 days 235 lunations is 6939.69 days. The Metonic cycle may be written as 19 x 18.618 x 19.618 days. 7 19