Rosh Hashanah - Wikipedia

Rosh Hashanah is the Jewish spiritual New year[?]. The Mishnah sets this day aside as the new year for calculating calendar years, sabbatical and jubilee years, vegetable tithes, and tree-planting (determining the age of a tree). According to rabbinic tradition, the creation of the world was finished on Tishri 1.

This holiday is characterized by the blowing of the shofar, a trumpet made from a ram's horn. During the afternoon of the first day occurs the practice of tashlikh, the symbolic casting away of sins by throwing either stones or bread crumbs into the waters. Rosh Hashanah is traditionally observed for a second day as well, if one is outside of the biblical boundaries of the land of Israel.

Erev Rosh Hashanah (the evening on which the holiday starts) is on the 29th of the month of Elul; the first full day on the first day of the month of Tishri 1. It occurs 163 days before Pesach (Passover). In the Gregorian calendar at present, Rosh Hashanah cannot occur before September 5, when it occurred in 1899 and will occur again in 2013. After the year 2089[?], the differences between the Hebrew Calendar and the Gregorian Calendar will force Rosh Hashanah to be not earlier than September 6. Rosh Hashanah cannot occur later than October 5, when it occurred in 1967 and will again occur in 2043.

The denominations of Reconstructionist Judaism and Reform Judaism generally celebrate only the first day of Rosh HaShanah; these movements regards Jewish law relating to these holidays as important, but no longer binding. Orthodox Judaism and Conservative Judaism observe both the first and second days, and hold that Jewish law relating to these (and all other holidays) are still normative (i.e. to be accepted as binding.)