Day and Night
Beginning of Night
Three Periods of History
The history of a Jewish Calendar is divided into three periods: the Biblical, the Talmudic, and the post Talmudic. During the Biblical period the understanding of the Calendar was based entirely upon the observation of the sun and the moon. The Talmudic period rested upon observation and reckoning, and the post Talmudic period rested entirely upon reckoning. The Hebrews studied astronomy very carefully because of their intense need for accurate dates in keeping the festivals. The Lord gave the command in Deuteronomy 16:1:
"keep the month of Aviv,"
and made it necessary for the Hebrews to become very acquainted with the position of the sun. Also the command:
"observe the moon and sanctify it,"
made it necessary for the Hebrews to study the phases of the moon.
Originally, the Hebrews employed numerals to distinguish one month from another. The month by which the spring season (Aviv) commenced was the first month (Exod 12:2; Deut 16:1), the other months were referred to as the second month, the third month, etc. The Bible reveals some traces of names of months: Aviv is revealed as the first month; Ziv, the second month (1 Kings 6:1); Etanim, the seventh month (1 Kings 8:2); and Bul, the eigth month ( 1 Kings 6:38).
Note: In post exilic books Babylonian names are employed.
The Jewish Calendar in Ancient Hebrew History
Bible History Online