years had the same length of 365 days. The beginning of the calendar year was recorded on the day of the first visible (or heliacal, occurring against the background of dawn) rising of Sirius (Canis Major).

The ancient Indo-Europeans, who originated as a linguistic group in the Southern Urals, had ideas about the calendar. During the Vedic period, the ancient Indo-European Indians developed sophisticated timekeeping methodology and calendars for Vedic rituals. For example, the Vedanga calendar in ancient India was based on astronomical research from the Vedic period and was not borrowed from other cultures.

A large number of calendar systems in the Ancient Near East were based on the Babylonian calendar dating from the Iron Age, among them the calendar system of the Persian Empire, which dates back to the Indo-European culture, which in turn gave rise to the Zoroastrian calendar. The Babylonian New Year began with the first new moon after the northern equinox. The ancient celebrations lasted 11 days.

The basis of ancient Greek chronology was the counting of time according to the Olympiads – national festivals and games that took place once every 4 years in Olympia. The era of the Olympics is taken to be the summer of 776 BC; According to legend, the first Olympics took place this year.

In ancient times, calendars were lunisolar, depending on the introduction of intermediate months to align the solar and lunar years. This was largely observational, but there may have been early attempts to algorithmically model intercalation structure, as evidenced by the fragmentary 2nd century Coligny calendar. Depending on the calendar used, new years are often classified as lunar new years, lunisolar new years, or solar new years.

The Roman calendar was reformed by Julius Caesar in 46 BC. His "Julian" calendar no longer depended on the observation of the new moon, but followed the algorithm of introducing a leap day every four years. This led to the separation of the calendar month from the lunar period.

According to the ancient Roman calendar, the year consisted of 10 months, with March being considered the first month, in honor of the god Mars. At the turn of the 7th and 6th centuries. BC e. A calendar was borrowed from the Etruscans, in which the year was divided into 12 months: January and February followed December. The months of the Roman calendar had the following names:

mensis – month

Martius – March (in honor of the god Mars)

Aprilis – April (warmed by the Sun)

Maius – May (named after the goddess Maya)

Junius – June (named after the goddess Juno).

Quintflis – fifth (from 44 BC. Julius – July, in honor of Julius Caesar)

Sextllis – sixth (from 8 AD Augustus – August, in honor of the Roman emperor Augustus)

September – September (seventh)

October – October (eighth)

November – November (ninth)

December – December (tenth)

Januarius – January (named after the god Janus, the name of God is associated with the words janus covered passage and janua door; god of doors, entrance and exit, every beginning).

Februarius – February (month of purifications, from februare to cleanse, to make an atoning sacrifice at the end of the year).

Julius Caesar in 46 BC e., on the advice of the Egyptian astronomer Sosigenes, carried out a radical reform of the calendar according to the model adopted in Egypt. A four-year solar cycle was established (365 + 365 + 365 + 366 = 1461 days) with unequal lengths of months, still accepted today: 30 days (April, June, September, November) and 31 days (January, March, May, July, August, October, December), in February – 28 days for three years and 29 days for the fourth year. Caesar moved the beginning of the year to the first of January, since on this day the consuls took office and the Roman economic year began.

The Gregorian calendar, introduced in 1582 under Pope Gregory XIII, corrected most of the remaining differences between the Julian calendar and the solar year.

Several contemporary proposals have been put forward to reform the modern calendar, such as the Universal Calendar, the International Fixed Calendar, the Holocene Calendar, and the Hanke–Henry Permanent Calendar. Such ideas are discussed from time to time, but they fail to gain popularity due to the loss of continuity and massive upheaval that their implementation would entail, as well as their impact on the cycles of religious activity.

Other cultures celebrate their traditional or religious New Year according to their customs, usually (though not always) as they use a lunar or lunisolar calendar. Well-known examples include Chinese New Year, Islamic New Year, Tamil New Year (Puthandu) and Jewish New Year. India, Nepal and other countries also celebrate New Year according to their own calendars, which vary according to the Gregorian calendar.

During the Middle Ages in Western Europe, when the Julian calendar was still in use, authorities moved New Year's Day, depending on the region, to one of several other days, including March 1, March 25, Easter (a nomadic holiday), September 1, and December 25 . Since then, many national civil calendars in the Western world and beyond have switched to using one fixed date to celebrate the New Year, January 1 – most of them have done this by adopting the Gregorian calendar.

January 1: First day of the civil year according to the Gregorian calendar used by most countries. Contrary to popular belief in the West, the civil New Year, celebrated on January 1, is not an Orthodox Christian religious holiday. The Eastern Orthodox liturgical calendar does not provide for the celebration of the New Year. Although the liturgical calendar begins on September 1, the beginning of a new cycle is also not associated with any special religious rites. However, Orthodox peoples can celebrate the New Year as part of civil holidays. Those who adhere to the Revised Julian calendar (which synchronizes dates with the Gregorian calendar), including Bulgaria, Cyprus, Egypt, Greece, Romania, Syria and Turkey, observe both religious and civil holidays on January