International Astrology Day, is observed annually on March 20th, and is celebrated by astrologers and astrology enthusiasts. It is seen by astrologers as the beginning (first day) of the astrological year. It is the first full day of the astrological sign of Aries and thus marks the beginning of the tropical Zodiac.International Astrology Day is celebrated/observed depending on the exact day that the Northward equinox actually occurs (Spring equinox in the Northern hemisphere, Fall equinox in the Southern hemisphere). This varies year to year between March 19–22, though it usually falls on March 20 or March 21.The date of the holiday occurs at the same time of the Iranian new year (Norouz), which is celebrated in many places throughout the Middle East and Central Asia. It also corresponds with the beginning of the Bahá’í calendar, which is celebrated as Bahá’í Naw-Rúz. Other holidays occurring around this time include Ostara (amongst neopagans), Chunfen in China, and Vernal Equinox Day (a public holiday in Japan), among others.
The Northward equinox (or March equinox) is the equinox on the earth when the Sun appears to cross the celestial equator, heading northward. The Northward equinox is the vernal equinox in the Northern Hemisphere and the autumnal equinox in the Southern Hemisphere. It is also The point where the horizon crosses the sun’s disk at the celestial equator northwards is called the first point of Aries. However, due to the precession of the equinoxes, this point is no longer in the constellation Aries, but rather in Pisces. By the year 2600 it will be in Aquarius (hence the phrase “the dawning of the Age of Aquarius”). The Northward equinox passed from Taurus into Aries 1865 BC, and passed into Pisces in year 67 BC, will pass into Aquarius in year 2597, and Capricorn in 4312. The equinox can be as early as March 19 or as late as March 21, the precise time being about 5 hours 49 minutes later in a common year, and about 18 hours 11 minutes earlier in a leap year, than in the previous year. It is the balance of common years and leap years that keeps the calendar date of the equinox from drifting more than a day from 20 March each year.
During the equinox, the horizon crosses the sun’s disk directly in the east at dawn and crosses directly in the west at dusk. However, because of refraction the horizon will usually appear slightly below the sun at the moment when its “true” middle is rising or setting. For viewers at the north or south poles, the horizon moves virtually horizontally along or below the sun, not obviously rising or sinking apart from the movement in “declination” (and hence altitude) of a little under a half (0.39) degree per day. For observers in either hemisphere not at the poles, the further one goes in time away from the March equinox in the 3 months before that equinox, the more to the south the Sun is seen, and for the 3 months afterwards the sun is seen more and more to the north. It is one point in time commonly used to determine the length of the tropical year. The length of the Northward equinox solar year is relatively stable in the time from 6000 BC to 10000 CE at 47:37 to 49:20 in excess of 365 days and 5 hours. However When tropical year measurements from several successive years are compared, variations are found which are due to nutation, and to the planetary perturbations acting on the Sun.
The March Equinox also has an effect on the calender and traditions, for instance The Persian Calendar begins each year at the Northward equinox, observationally determined at Tehran. The Indian National Calendar starts the year on the day next to the Vernal Equinox on March 22 (March 21 in leap years) with a 30-day month (31 days in leap years), then has 5 months of 31 days followed by 6 months of 30 days.The Julian calendar reform lengthened seven months and replaced the intercalary month with an intercalary day to be added every four years to February. It was based on a length for the year of 365 days and 6 hours (365.25 d), while the tropical year is about 11 minutes and 14 seconds less than that. This had the effect of adding about three quarters of an hour every four years. The effect accumulated from 325 until by the 16th century, when the northern vernal equinox fell on March 10 or 11. In Abrahamic traditionThe Jewish Passover usually falls on the first full moon after the Northern Hemisphere vernal equinox, although occasionally (7 times every 19 years) it will occur on the second full moon.The Christian churches calculate Easter as the first Sunday after the first full moon on or after the March equinox. The official church definition for the equinox is March 21; however, as the Eastern Orthodox Churches use the older Julian calendar, while the Western Churches use the Gregorian calendar, both of which designate March 21 as the equinox, the actual date of Easter differs. The earliest possible Easter date in any year is therefore March 22 on each calendar. The latest possible Easter date in any year is April 25t