According to the Tropical system of astrology, the Sun enters the sign of Aries when it reaches the northern vernal equinox, which occurs around March 21. Due to the fact that the Earth takes approximately 365.25 days to go around the Sun, the precise time of the equinox is not the same each year, and generally will occur about 6 hours later each year, with a jump of a day (backwards) on leap years. Since 1900 the vernal equinox date ranged from March 20 at 08h (2000) to March 21 at 19h (1903) (all times UTC).