Nowruz

Nowruz (Persian: نوروز, Iranian Persian: [noːˈɾuːz], lit. 'New Day') is the Iranian or Persian New Year. Historically, it has been observed by Iranian peoples, but is now celebrated by many ethnicities worldwide. It is a festival based on the Northern Hemisphere spring equinox, which marks the first day of a new year on the Iranian calendars and the currently used Hijri calendar; it usually coincides with a date between 19 March and 22 March on the Gregorian calendar.

The roots of Nowruz lie in Zoroastrianism, and it has been celebrated by many peoples across West Asia, Central Asia, the Caucasus and the Black Sea Basin, the Balkans, and South Asia for over 3,000 years. In the modern era, while it is observed as a secular holiday by most celebrants, Nowruz remains a holy day for Zoroastrians, Baháʼís, and Ismaʿili Shia Muslims.

For the Northern Hemisphere, Nowruz marks the beginning of spring. Customs for the festival include various fire and water rituals, celebratory dances, gift exchanges, and poetry recitations, among others; these observances differ between the cultures of the diverse communities that celebrate it.

The first day of the Iranian calendar falls on the March equinox, the first day of spring, around 21 March. In the 11th century AD the Iranian calendar was reformed by Omar Khayyam in order to fix the beginning of the calendar year, i.e. Nowruz, at the vernal equinox. Accordingly, the definition of Nowruz given by the Iranian astronomer Tusi was the following: "the first day of the official New Year [Nowruz] was always the day on which the sun entered Aries before noon." Nowruz is the first day of Farvardin, the first month of the Iranian solar calendar, which is the official calendar in use in Iran, and formerly in Afghanistan.

The United Nations officially recognized the "International Day of Nowruz" with the adoption of Resolution 64/253 by the United Nations General Assembly in February 2010.

The word Nowruz is a combination of the Persian words نو (now, meaning 'new') and روز (ruz, 'day'). Historically, the word was vocalized in Classical Persian as Nawrōz, and in Middle Persian as Nōgrōz. The modern pronunciation varies among Persian dialects, with Dari and Tajiki (the eastern dialects) using the pronunciations [nawˈɾoːz] and [næʋˈɾɵz] respectively, and Iranian Persian (the western dialect) using [nowˈɾuːz] (in particular in the Tehrani accent: [noːˈɾuːz]). A variety of spellings for the word Nowruz exist in English-language usage, including Norooz, Novruz, Nowruz, Navruz, Nauruz and Newroz.

Nowruz's timing is based on the vernal equinox. In Iran, it is the day of the new year in the Solar Hijri algorithmic calendar, which is based on precise astronomical observations, and moreover use of sophisticated intercalation system, which makes it more accurate than its European counterpart, the Gregorian calendar.

Each 2820-year great grand cycle contains 2,137 normal years of 365 days and 683 leap years of 366 days, with the average year length over the great grand cycle 365.24219852. This average is just 0.00000026 (2.6×10⁻⁷) of a day—slightly more than 1/50 of a second—shorter than Newcomb's value for the mean tropical year of 365.24219878 days, but differs considerably more from the current average vernal equinox year of 365.242362 days, which means that the new year, intended to fall on the vernal equinox, would drift by half a day over the course of a cycle. As the source explains, the 2820-year cycle is erroneous and has never been used in practice.