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The Iranian calendar (sometimes also known as Persian calendar or solar Islamic calendar) is a solar calendar currently used in Iran and Afghanistan.
Today Iran uses a solar calendar with a system of leap years. Like the Gregorian calendar it is designed to approximate the vernal equinox tropical year of about 365.2424 days. The Iranian calendar is a more accurate approximation than the Gregorian calendar, but has a more complicated leap year rule. The Iranian calendar was devised in the 11th century by a panel of scientists including Omar Khayyam, one of the foremost mathematicians and astronomers of his time (but today he is better known in the West for his poetry).
The Iranian calendar was reintroduced in Persia in the year 1922, while Afghanistan adopted the calendar in 1957, using the Arab names of the zodiacal signs for the corresponding months of the Persian calendar.
The Iranian solar calendar year begins with the midnight closest to the instant of the or Northern spring equinox, when the sun enters the northern hemisphere; in other words, the start of Spring in the northern hemisphere. The calendar consists of 12 months with Persian names. The first six months are 31 days each, the next five 30 days, and the last month has 29 days but 30 days in leap years. The reason the first 6 months have 31 days and the rest 30, is not a random decision -- it has to do with the fact that the sun moves slightly more slowly along ecliptic in the northern spring and summer than in the northern autumn and winter.
The Persian new year is determined by noon-time observation of the Northern spring equinox. If between two consecutive noons the sun's altitude rises through its equinoctial altitude then the first noon is on the last day of one calendar year and the second noon is on the first day ( NorouzNorouz (alternative spellings: Norooz, Noruz, Naw-Ruz, Nowrouz,. from Persian no new + rooz day meaning "new day"] is the traditional Iranian festival of the New Year which starts at the exact moment of the vernal equinox, commencing the start of the spri) of the next calendar year.
Typically leap yearA leap year (or intercalary year is a year containing an extra day or month in order to keep the calendar year in sync with an astronomical or seasonal year. Seasons and astronomical events do not repeat at an exact number of days, so a calendar which hads are devised and used by various solar calendar systems, usually every four years. Four-year leap years add 0.25 day to each year in the period. But that is a slight overcompensation compared to the actual behaviour of the sun. Remedying this overcompensation, after about every seven four-year leap years, the Persian solar calendar produces a five-year leap year, thus following a thirty-three year cycle for many centuries before interruptions by single twenty-nine year subcycles.
This general picture of the Persian calendar's leap-year behaviour contrasts with other ill-informed predictive algorithms which are based on confusion between the astronomers average tropical year (365.2422 days, approximated with mistaken near 128-year cycles) and the mean interval between spring equinoxes (365.2424 days, approximated here with a near 33-year cycle).
The PersianPersian , also known as Farsi (local name), Parsi Tajiki or Dari is a language spoken in Iran, Tajikistan, Afghanistan and Uzbekistan. It has official-language status in the first three countries. There are over 75 million native speakers. It belongs to t names are included in the parentheses.
The first day of this calendar year is also the day of the greatest festival of the year in Iran called NorouzNorouz (alternative spellings: Norooz, Noruz, Naw-Ruz, Nowrouz,. from Persian no new + rooz day meaning "new day"] is the traditional Iranian festival of the New Year which starts at the exact moment of the vernal equinox, commencing the start of the spri (a single word made up of two parts, no and rouz, meaning "new day").
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