September is the ninth month of the year in the Gregorian Calendar and one of four Gregorian months with 30 days.
September begins in western tropical astrology with the sun in the sign of Virgo and ends in the sign of Libra. Astronomically speaking, the sun actually begins in the constellation of Leo and ends in the constellation of Virgo.
In Latin, septem means "seven". The origin of the name may also be attributed to Vedic culture. In sanskrit, Sapta refers to "seven" and Ambar means "sky". "Sapt-Ambar" referred to the seventh sky or month in the Vedic culture.
September was also the seventh month of the Roman calendar until 153 BC.
info: Wikipedia