Depiction of the 19 years of the Metonic cycle as a wheel, with the Julian date of the Easter New Moon, from a 9th-century computistic manuscript made in St. Emmeram's Abbey (Clm 14456, fol. 71r) For astronomy and calendar studies, the Metonic cycle or Enneadecaeteris (from Ancient Greek words meaning "nineteen years") is a period of very close to 19 years … [Read more...]