Why does humanity need a calendar? This is a question that does not require an answer. Without it, people would get confused over time, completely unaware of when certain events on the planet happened, are happening or are planned in the future. Not only years and months, but even days, minutes, seconds need to be counted. For this, the ancients came up with the idea of systematizing time. There have been a huge number of different calendars on the old Earth throughout the history of mankind.
One of them was Julian. It was used by Europeans until 1582, and then was replaced by the order of Gregory XIII - the Pope of Rome - with the Gregorian calendar. And the reason turned out to be weighty: the Julian date sinned with inaccuracy. Why was the old calendar imperfect, and how did you manage to solve this problem? This will be discussed.
Tropical year
A calendar is accurate when it matches natural astronomical cycles. In particular, the year must coincide with the period during which the Earth makes a complete revolution around the Sun. According to astronomical data, this period of timeapproximately equal to 365 days and 6 hours. This is the so-called tropical year, which is the basis of the chronology. As you know, the usual year of our modern calendar has 365 days. Therefore, every four years there is one more day. This is where February 29 comes from in leap years. This is done to align the tropical and calendar years.
In the time of Gregory XIII, no one knew about the periods of the Earth's rotation, but there were their own ways of determining calendar accuracy. For the ministers of the Church, it was very important that the spring equinox, according to which the time of the onset of Christian Easter was determined, come on the same day, that is, as expected, on March 21. But once it turned out that the indicated date in the Julian calendar differs from the tropical one by 10 days. The spring equinox falls on March 11th. To eliminate this discrepancy, they introduced a calendar, just named after Gregory XIII.
Roman calendar
The predecessor of the Julian was the Roman calendar, developed in ancient times on the basis of knowledge borrowed from the priests of Ancient Egypt. The year, according to this chronology, was counted from January 1. And this coincided with the Julian date of its beginning and with later European traditions.
However, in those days they still did not know how to count astronomical cycles with great accuracy. Therefore, the year, according to the Roman calendar, consisted of only 355 days. The ancients noticed this discrepancy in order to align their dates with the day of springequinoxes, at the end of February additional months were inserted as needed. But decisions about this by a college of Roman priests were not always made carefully, often adjusted for political rather than astronomical considerations. That's why there were significant errors.
Julius Caesar's calendar reform
A more accurate calendar, named Julian in honor of Julius Caesar, was compiled by Alexandrian astronomers and adopted in ancient Rome in 45 BC. He synchronized the cycles of nature and the human system of counting years, months and days. The Julian date for the vernal equinox now followed the tropical calendar, with a year of 365 days. Also, with the introduction of the new chronology, an additional day appeared, which appeared in the calendar every four years.
And he ran from those already mentioned, not previously taken into account by the ancients, the astronomical six hours needed for the Earth to complete its rotation around the Sun. This is how leap years and the Julian date of an extra day in February appeared.
Where did the error come from
But if the accuracy back in those days was restored, and the calendar of the ancients became very similar to our modern one, how did it happen that in the time of Gregory XIII the need for reform arose again? How did the Julian date of the vernal equinox amount to a full 10 days?
It's very simple. Extra 6 hours, of which every four years an additional one runsthe day of leap years, in a more accurate measurement, as it turned out later, is only 5 hours 48 minutes and about 46 seconds. But this time interval also varies, it becomes more or less from year to year. These are the astronomical features of the rotation of our planet.
Those 11 minutes and a few seconds were completely invisible for a long time, but after centuries they turned into 10 days. That is why the ministers of the Church in the 16th century sounded the alarm, realizing the need for reform and translation of Julian dates into the days of the new calendar.
Recognition of the Gregorian calendar
By order of the Pope in 1582 in October, after the 4th, the 15th came immediately. This brought the church calendar in line with the natural cycles of nature. Thus, the dates of the Julian calendar were translated into the new Gregorian.
But such changes were not accepted by everyone and not immediately. The reason for this was religious considerations, because just at that time the Protestant anti-Catholic movement was gaining strength. And therefore, the adherents of this trend did not want to obey the decrees of the Pope. The reform of the calendar in Europe stretched over several centuries. In England and Sweden, a new system of chronology was adopted only in the middle of the 18th century. In Russia, this happened even later, after the October Revolution in January 1918, when a decree signed by V. I. Lenin.
Orthodox calendar
But the Orthodox Church in Russia, which did not submit to the Romandad, did not want to agree with the decree of the Soviet government. And because the Christian calendar even in those days has not changed. Its reform has not yet been carried out even to this day, and church holidays continue to be celebrated according to the so-called old style. The same traditions are supported by the Serbian and Georgian Orthodox Churches, as well as Catholics in Ukraine and Greece.
The Gregorian date can be converted to the Julian date by subtracting 13 days from the accepted number. That is why Christmas in Russia is celebrated not on December 25, but on January 7, and the old New Year comes almost two weeks after the calendar one.
