Aries (♈) /ˈɛəriːz/ (meaning "ram") is the first astrological sign in the Zodiac, spanning the first 30 degrees of celestial longitude (0°≤ λ <30º). Under the tropical zodiac, the Sun transits this sign between March 21 and April 20 each year. This time duration is exactly the first month of Solar Hejri calendar (Farvardin). Under the sidereal zodiac, the sun currently transits Aries from 15 April to 15 May (approximately).
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).
Individuals born during these dates, depending on which system of astrology they subscribe to, may be called Arians or Ariens.