The Hebrew Months
The Hebrew Calendar is a lunisolar calendar, or fixed lunar year, based on twelve lunar months of twenty-nine or thirty days, with an intercalary lunar month added seven times every nineteen years (once every two to three years) to synchronize the twelve lunar cycles with the slightly longer solar year. Each Hebrew lunar month starts with the new moon. Although originally the new lunar crescent had to be observed and certified by witnesses, the moment of the new moon is now approximated arithmetically. The Hebrew Calendar is an official calendar for various civil purposes in Israel.
The Bible does not give names to the months, but rather assigns them ordinal numbers: "the first month" (the Exodus from Egypt, later to be called the month of Nisan), "the second month," and the like. As time passed, they were given Hebrew names that all but four were subsequently lost. During the Babylonian exile, the Jews began to call the months by the Babylonian-Akkadian names that are mentioned in the later Biblical books and that are still used to the present day. During each month the sun is situated in a special constellation of stars known as the mazal (sign of the Zodiac) of the month. The twelve regular months are: Nisan (30 days), Iyar (29 days), Sivan (30 days), Tammuz (29 days), Av (30 days), Elul (29 days), Tishrei (30 days), Marcheshvan (29 or 30 days), Kislev (29 or 30 days), Tevet (29 days), Shevat (30 days), and Adar (29 days). In the leap years an additional month, Adar Alef (30 days) is added after Shevat, and the regular Adar is referred to as Adar Bet.
The present counting method for years uses the Anno Mundi epoch (Latin for "in the year of the world"), abbreviated AM and also referred to as the Hebrew era. E.g. the Hebrew year that began at sunset Sep. 28, 2011 and ended on Sep. 16, 2012 was year 5772.
The 12 stamps sheet was issued in 2002, each stamp dedicated to a certain month of The Hebrew Calendar. Designer: Miri Sofer.