The Julian calendar (or Julian calendar) was a calendar introduced by Caius Iulius Caesar - after the founding of Rome in 709 (45 BC) - and was based on the Egyptian calendar, which had been in use for almost three thousand years, making it much more accurate and simpler. it was in other contemporary calendars, including the Romans.
Even in ancient times, there was a need for the largest unit of time, the calendar year, to be as long as the combined length of the seasons. The calendar used until the time of Iulius Caesar did not meet this requirement; it deviated more and more from the walk of the Sun. As a result, for example, an originally spring holiday had already fallen into summer. The discrepancy necessitated re-regulation of time.
Julius Caesar BC There were two elements to the calendar reform ordered in 45. In order to correct the accumulated calendar “delay”, it extended the 44th year and clarified the previously imperfect method of calculation in order to preserve the restored order. The calendar was created with the help of the Greek astronomer Alexandria, Sosigen, and was intended to approximate the year in orbit (as determined by Hipparchus). Sosigenes set the day of day-night equality at March 21, 709, according to Roman time, but the beginning of the year remained March 1.
The new calculation was already pretty close to the actual length of the year, but it still caused a difference of one day every 128 years. The slow slip caused more and more trouble in connection with church holidays, so it took place in the 16th century. century to introduce the Gregorian or Gregorian calendar. Catholic countries adopted the new method of calculation faster, Protestants more slowly, some Orthodox states only in the XX. century.
Some of the Orthodox churches still use the Julian calendar as their church calendar, while others have now switched to the new Julian calendar, which is almost identical to the Gregorian calendar. For example, this is why Orthodox churches left on the Julian calendar celebrate Christmas on a day other than the Gregorian calendar.
From the Roman calendar to the Julian calendar
The Romans originally used a 10-month calendar based on the orbit of the Moon, in which each month was 29 or 30 days old. The year thus consisted of 295 days. The memory of this old calendar is preserved by the names of the months formed from the Latin numeral: September - 7; october - 8; November - 9; December - 10; the first ice of the year was March.
In a tropical year (or year of the year), of course, there are many more days in a year, and it sounds unusual to us that the number of days in a year should not fall close to 365. The great difference is possible because the Romans at that time did not consider it important to count the two winter months because they were agriculturally useless.
Later, King Numa Pompilius in the i. e. It also introduced the 11th and 12th months in the 7th century, the “10th. month ”and the first month under the previous calculation system, March. So the year is 355 days old. Compared to the tropical year, there is still a difference of 10 days. The deficit was corrected by adding another month every two years between 23 and 24 February. The ordering of the correction was the right of the current power, of which, unfortunately, there are many abuses, ye. the extension of the consuls' mandate was also favored at the cost of extending the year.
This system dates back to the beginning of the 19th century BC. In the 1st century, it proved to be completely unsustainable, so it had to be modernized.
Thus, Julius Caesar took two important steps based on the suggestions of Alexandria astronomer. On the one hand, it ordered that the 90 days missing to start the year be added to the year of the calendar reform.