Why does the Jewish faith calender have a different time-scale to?
The Jewish calendar is based upon the rotation of the Earth on its axis, the revolution of the moon around the Earth (29 1/2 days) and the revolution of the Earth around the sun (12.4 lunar months). The lunar month on the Jewish calendar begins when the first sliver of moon becomes visible after the dark of the moon. The problem with strictly lunar calendars is that there are approximately 12.4 lunar months in every solar year, so a 12-month lunar calendar loses about 11 days every year and a 13-month lunar gains about 19 days every year. The months on such a calendar “drift” relative to the solar year. On a 12 lunar month calendar, the month of Nissan, which is supposed to occur in the Spring, would occur 11 days earlier each year, eventually occurring in the Winter, the Fall, the Summer, and then the Spring again. To compensate for this drift, an extra month was occasionally added. The month of Nissan would occur 11 days earlier for two or three years, and then would jump forward 29
