Nisan

Nisan is the first month of the Hebrew year in the reckoning used for festivals, falling in early spring, roughly March to April, and aligned in tradition with the sign of Aries. Its counting from first place comes directly from the Torah, which sets the month of the Exodus at the head of the months. Nisan is dominated by Passover (Pesach), which begins on the fifteenth and commemorates the deliverance of Israel from Egypt, kept with the seder and the eating of unleavened bread. The name Nisan, adopted during the Babylonian exile, is glossed with the sense of movement and sprouting, fitting the barley harvest and the spring season. The Hebrew calendar is lunisolar, its months set by the moon but kept in step with the solar year by an added month in leap years. These are the observances of the Jewish calendar tradition.

Because the Torah itself counts Nisan as the first month while the civil new year, Rosh Hashanah, falls in the seventh month, Tishrei, the Hebrew calendar runs two parallel numbering systems simultaneously, a festival count beginning at Nisan and a civil count beginning at Tishrei, both attested in different biblical and rabbinic contexts; the Mishnah, compiled around 200 CE, explicitly names four distinct new years for different legal purposes, of which Nisan 1 and Tishrei 1 are the two most prominent. The name Nisan itself, along with the other Babylonian-derived month names used throughout the modern Hebrew calendar, replaced older biblical month names, mostly ordinal (the first month, the second month) with a small number of named exceptions such as Aviv and Ziv, during and after the Babylonian exile of the sixth century BCE, a linguistic borrowing the Talmud itself acknowledges directly.

The name comes from the Akkadian Nisannu, one of the Babylonian month names adopted wholesale into Hebrew usage. The month runs a fixed 30 days in every year.

The month names are Babylonian. Twelve of them are the Akkadian month names taken into Hebrew during and after the exile, and the biblical books of the return use them freely while the earlier books generally number the months or use a small set of older Canaanite names. The atlas records the borrowing rather than presenting the names as native, because it is one of the clearest visible marks the exile left on Jewish practice.

The Jewish calendar as now kept is calculated rather than observed. Month lengths are fixed by rule except for Cheshvan and Kislev, which absorb the adjustment and may run 29 or 30 days, and a thirteenth month is added in seven years out of nineteen on a fixed cycle so that Passover stays in the spring. A further set of rules, the postponements, shifts Rosh Hashanah off certain weekdays, which is why the year has six possible lengths rather than two.

Nisan is the first month of the year in the biblical ordering, which counts from the spring as the Torah directs, while the year number changes in the autumn at Rosh Hashanah in Tishrei. Both conventions are genuine and both are in use, which is why Nisan is called the first month in a calendar whose new year falls in the seventh.