On the doorstep new years, when one year succeeds another, we do not even think about what style we live by. Surely from the lessons of history, many of us remember that once there was a different calendar, later, people switched to a new one, and began to live in a new way. style.

Let's talk about how these two calendars differ: Julian and Gregorian .

The history of the creation of the Julian and Gregorian calendars

To make time calculations, people came up with a chronology system, which was based on the frequency of movement. celestial bodies, so was created calendar.

Word "calendar" comes from the Latin word calendarium which means "Debt book"... This is due to the fact that the debtors paid their debt on the day calend, so the first days of each month were called, they coincided with new moon.

So, at ancient Romans every month had 30 days, or rather, 29 days, 12 hours and 44 minutes. At first, this calendar had ten months, hence, by the way, the name of our last month of the year - December(from latin decem- tenth). All months were named after Roman gods.

But, starting from the III century BC, in ancient world a different calendar was used, based on a four-year lunisolar cycle, he gave an error in the value solar year one day. In Egypt they used solar calendar compiled from observations of the Sun and Sirius. The year according to it was three hundred sixty five days... It consisted of twelve months by thirty days each.

It was this calendar that became the basis Julian calendar... It is named after the emperor Guy Julius Caesar and was introduced to 45 BC... The beginning of the year according to this calendar began January 1st.

Guy Julius Caesar (100 BC - 44 BC)

Existed Julian calendar more than sixteen centuries, while in 1582 G. Pope Gregory XIII did not offer new system chronology. The reason for the adoption of the new calendar was a gradual shift in relation to the Julian calendar of the day of the vernal equinox, by which the date of Easter was determined, as well as the inconsistency of the Easter full moons with the astronomical ones. Chapter Catholic Church believed that it was necessary to determine the exact calculation of the celebration of Easter, so that it fell on a Sunday, and also to return the vernal equinox to the date of March 21.

Pope Gregory XIII (1502-1585)

However, in 1583 year Cathedral of the Eastern Patriarchs in Constantinople did not accept new calendar, since it contradicted the main rule by which the day of the celebration of Christian Easter is determined: in some years, Christian Easter would come earlier than the Jewish one, which was not allowed by the canons of the church.

However, most European countries followed the call of Pope Gregory XIII and switched to new style chronology.

Go to Gregorian calendar brought about the following changes :

1. to correct the accumulated errors, the new calendar at the time of adoption immediately shifted the current date by 10 days;

2. a new, more precise, leap year rule has become effective - a leap year, that is, it contains 366 days if:

The year number is a multiple of 400 (1600, 2000, 2400);

The year number is a multiple of 4 and not a multiple of 100 (… 1892, 1896, 1904, 1908…);

3. the rules for calculating Christian (namely, Catholic) Easter were changed.

The difference between the dates of the Julian and Gregorian calendars increases by three days every 400 years.

History of chronology in Russia

In Russia, before Epiphany, the new year began in March, but from the 10th century, the New Year began to be celebrated in September, in Byzantine church calendar... However, people accustomed to the centuries-old tradition continued to celebrate New Year with the awakening of nature - in the spring. While the king Ivan III v 1492 year did not issue a decree stating that the New Year is officially postponed to beginning of autumn... But this did not help, and the Russian people celebrated two new years: in spring and autumn.

Tsar Peter the Great striving for everything European, December 19, 1699 year issued a decree that the Russian people, together with the Europeans, celebrate the New Year January 1st.

But, at the same time, in Russia it still remained valid Julian calendar adopted from Byzantium with baptism.

February 14, 1918, after the coup, all of Russia switched to new style, now the secular state began to live according to Gregorian calendar... Later in 1923 year, the new authorities tried to transfer to the new calendar and the church, however To His Holiness the Patriarch Tikhon managed to keep the traditions.

Today Julian and Gregorian calendars continue to exist together. Julian calendar enjoy Georgian, Jerusalem, Serbian and Russian churches, whereas Catholics and Protestants guided by Gregorian.

As you know, the Russian Orthodox Church uses the Julian calendar in its divine services, while Russian state, together with most countries, has been using the Gregorian calendar for some time now. At the same time, both in the Church itself and in society from time to time voices are heard calling for a transition to a new style.

The arguments of the defenders of the Julian calendar, which can be found in the Orthodox press, basically boil down to two. The first argument is that the Julian calendar is sanctified by centuries of use in the Church, and there is no compelling reason to abandon it. The second argument: in the transition to a "new style" with the preservation of traditional Easter (the system for calculating the date of the Easter holiday), many incongruities arise, and violations of the liturgical charter are inevitable.

Both of these arguments are quite convincing for a believing Orthodox person. However, they do not seem to relate to the Julian calendar as such. After all, the Church did not create a new calendar, but adopted the one that already existed in the Roman Empire. What if the calendar were different? Perhaps, then, it was the other calendar that would have been consecrated by the liturgical use, and it was with this in mind that the Passover would have been compiled?

This article is an attempt to consider some aspects of the calendar problem, providing the reader with material for independent reflection. The author does not consider it necessary to hide his sympathy for the Julian calendar, but realizes that it is impossible to prove its advantage in any way. Just as the superiority of the liturgical Church Slavonic language over Russian or the icons of St. Andrei Rublev in front of Raphael's painting.

The presentation will be conducted in three stages: first summary conclusions, then a more detailed mathematical justification and, finally, a small historical sketch.

Any natural phenomenon can be used to measure time and compile a calendar if it is uniformly and periodically repeated: change of day and night, change of phases of the moon, seasons, etc. All these phenomena are associated with certain astronomical objects. In the book of Genesis we read: And God said: let there be lights in the firmament of heaven for ... times, and days, and years ... And God created two great lights: a greater one to rule the day, and a lesser one, to govern the night, and the stars(Genesis 1, 14-16). The Julian calendar is compiled just taking into account the three main astronomical objects - the Sun, the Moon and the stars. This gives reason to consider it a truly biblical calendar.

Unlike the Julian calendar, the Gregorian calendar takes into account only one object - the Sun. It is designed in such a way that the point of the vernal equinox (when the lengths of day and night are equal) would deviate as slowly as possible from the date of March 21. At the same time, the connection of the calendar with the Moon and the stars was destroyed; in addition, the calendar became more complicated and lost its rhythm (in comparison with the Julian).

Consider one property of the Julian calendar that has been most criticized. In the Julian calendar, the vernal equinox moves backwards along calendar dates at a rate of about 1 day in 128 years. (In general, the difference between the Julian and Gregorian dates is currently 13 days and increases by 3 days every 400 years.) This means, for example, that the day of the celebration of the Nativity of Christ, December 25, will eventually move to spring. But, firstly, this will happen in about 6,000 years, and secondly, and now in the southern hemisphere, Christmas is celebrated not even in spring, but in summer (since there December, January and February - summer months).

Taking into account all of the above, we can conclude that the statement "the Gregorian calendar is more accurate than the Julian" is far from indisputable. Everything here is determined by the accuracy criteria, and they can be different.

To substantiate the above statements, we present some astronomical and arithmetic reasoning and facts.

One of the main periods of time for us is the year. But it turns out that there are several different "types" of the year. Let us mention two that are most important for our consideration.

  • Sidereal, or stellar, year. This is what they mean when they say that the Sun passes through twelve zodiacal signs in a year. For example, St. Basil the Great (IV century) in his "Conversations on the Six Days" writes: "The solar year is the return of the Sun, due to its own movement, from famous mark into the same sign. "
  • Tropical year. It takes into account the changing seasons on Earth.

The Julian year averages 365.25 days, that is, it lies between the sidereal and tropical years. The Gregorian year averages 365.2425 days, it is very close to the tropical one.

In order to better understand the aesthetics and logic of the calendar, it is useful to highlight some of the problems that arise when creating it. Strictly speaking, the construction of the calendar includes two fairly independent procedures. The first is empirical: the duration of astronomical cycles should be measured as accurately as possible. (Note that the durations of the sidereal and tropical years were found with great accuracy in the 2nd century BC by the Greek astronomer Hipparchus.) The second procedure is already purely theoretical: based on the observations made, compose a time measurement system that, on the one hand, it would deviate as little as possible from the chosen space landmarks, and on the other hand, it would not be very cumbersome and complicated.

Suppose, for example, you want to create a calendar based on a tropical year (after measuring the duration of the last - 365.24220 days). It is clear that each year of such a calendar must contain either 365 or 366 days (in the latter case, the year is called a leap year). At the same time, we must try to ensure that, firstly, the average number of days in a year is as close as possible to 365.2422 and, secondly, that the rule of alternation of simple and leap years was as simple as possible. In other words, you need to define a cycle with a duration of N years, of which M will be leap years. In this case, firstly, the fraction m / n should be as close to 0.2422 as possible, and secondly, the number N should be as small as possible.

These two requirements contradict each other, since accuracy is achieved only at the cost of increasing the number N. simple solution the problem is the fraction 1/4, on which the Julian calendar is based. The cycle consists of four years, every fourth year (the ordinal number of which is evenly divisible by 4) is a leap year. The Julian year averages 365.25 days, which is 0.0078 days longer duration tropical year. In this case, the error in one day accumulates over 128 years (0.0078 x 128 ~ 1).

The Gregorian calendar is based on the fraction 97/400, i.e. there are 97 leap years in a 400-year cycle. Leap years are considered to be years, the ordinal number of which is either divisible by 4 and not divisible by 100, or is divisible by 400. The Gregorian year averages 365.2425 days, which is 0.0003 days longer than the duration of the tropical year. In this case, the error in one day accumulates over 3333 years (0.0003 x 3333 ~ 1).

From the foregoing, it is clear that the advantage of the Gregorian calendar over the Julian calendar is debatable even as it is oriented only to a tropical year - accuracy is achieved at the cost of complication.

Let us now consider the Julian and Gregorian calendars from the point of view of correlation with the Moon.

The change in the phases of the moon corresponds to a synodic, or lunar, month, which is 29.53059 days. During this time, all phases of the moon change - new moon, first quarter, full moon, last quarter. A whole number of months does not fit into one year without a remainder, therefore, a 19-year cycle was used to construct almost all operating lunisolar calendars, bearing the name of the Greek astronomer Meton (V century BC). In this cycle, the relation

19 years ~ 235 synodic months,

that is, if the beginning of a certain year coincides with the appearance in the sky new moon, then this coincidence will take place in 19 years.

If the year is Gregorian (365.2425 days), then the error of the Metonian cycle is

235 x 29.53059 - 19 x 365.2425 ~ 0.08115.

For the Julian year (365.25 days), the error is less, namely

235 x 29.53059 - 19 x 365.25 ~ 0.06135.

Thus, we find that the Julian calendar is better correlated with changes in the phases of the moon (see also: Klimishin I.A. ).

In general, the Julian calendar is a combination of simplicity, rhythm (a cycle lasting only 4 years), harmony (correlation immediately with the Sun, Moon and stars). It is pertinent to mention its practicality: the same number of days in each century and the continuous counting of time over two millennia (disrupted by the transition to the Gregorian calendar) simplify astronomical and chronological calculations.

Two surprising circumstances are associated with the Julian calendar. The first astronomical circumstance is the closeness of the fractional part of the length of the year (both sidereal and tropical) to such a simple fraction 1/4 (we suggest that the reader, familiar with methods of testing statistical hypotheses, calculate the corresponding probability). However still the second is more surprising circumstance - for all its merits, the Julian calendar was never used anywhere until the 1st century. BC

The predecessor of the Julian calendar can be considered the calendar used in Egypt for many centuries. In the Egyptian calendar, each year contained exactly 365 days. Of course, the error of this calendar was very large. For about one and a half thousand years, the day of the vernal equinox "ran" all the numbers of the calendar year (which consisted of 12 months of 30 days and five additional days).

About 1700 BC the northern part of the Nile Delta fell under the rule of the nomadic Hyksos tribes. One of the Hyksos rulers who made up the 15th dynasty of Egypt carried out a calendar reform. After 130 years, the Hyksos were expelled, the traditional calendar was restored, and since then, each pharaoh, ascending the throne, took an oath not to change the length of the year.

In 238 BC, Ptolemy III Everget (a descendant of one of the military leaders of Alexander the Great), who ruled in Egypt, tried to reform, adding an extra day every 4 years. This would make the Egyptian calendar almost identical to the Julian one. However, for unknown reasons, the reform was not implemented.

And now the time of the incarnation of God and the founding of the Church approached. Some of the participants in the events described by the evangelists have already walked the land of Palestine. From January 1, 45 BC, a new calendar was introduced in the Roman Empire by order of Gaius Julius Caesar (100-44). This calendar, now called Julian, was developed by a group of Alexandrian astronomers led by Sozigen. From then until the 16th century, that is, approximately 1600 years, Europe lived according to the Julian calendar.

In order not to deviate from our topic, we will not consider calendar systems. different countries and peoples. Note that some of them are rather unfortunate (one of the worst, it seems, was the calendar used in the Roman Empire before the introduction of the Julian). We will mention only one calendar, interesting in that it contains calendar year closer to the tropical than that of the later Gregorian. From 1079 to the middle of the XIX century. Iran had a Persian calendar developed by a commission led by the scientist and poet Omar Khayyam (1048-1123). The Persian calendar is based on the fraction 8/33, that is, the cycle is 33 years, of which 8 are leap years. Leap years were the 3rd, 7th, 11th, 15th, 20th, 24th, 28th and 32nd years of the cycle. Average duration of the year in the Persian calendar is 365.24242 days, which is 0.00022 more than in the tropical one. The error in one day accumulates over 4545 years (0.00022 x 4545 ~ 1).

In 1582, the Gregorian calendar was introduced by Pope Gregory XIII. During the transition from the Julian calendar to the Gregorian calendar, 10 days were thrown away, that is, after October 4, October 15 went immediately. The calendar reform of 1582 caused many protests (in particular, almost all universities in Western Europe spoke out against it). Nevertheless, for obvious reasons, Catholic countries almost immediately switched to the Gregorian calendar. The Protestants did this gradually (for example, Great Britain - only in 1752).

In November 1917, immediately after the Bolsheviks seized power in Russia, the question of the calendar was brought up for discussion by the Council of People's Commissars of the RSFSR. On January 24, 1918, the "Decree on the introduction of The Russian republic Western European calendar ".

Local Orthodox Churches adhered to the Julian calendar until the 1920s, when the Ecumenical (Constantinople) Patriarchate rejected it. The main purpose of this decision was, apparently, the celebration of Christian holidays together with Catholics and Protestants.

Over the next decades, the new style was adopted by most of the Local Churches, and the formal transition was made not to the Gregorian, but to the so-called New Julian calendar based on the fraction 218/900. However, until 2800, it completely coincides with the Gregorian.

It is expressed in the joint celebration of the Easter of Christ and the so-called rolling holidays associated with it (the only exception is the Finnish Orthodox Church, which celebrates Easter on the same day as Western Christians). The date of Easter is calculated according to a special lunisolar calendar, inextricably linked with the Julian one. In general, the method of calculating the date of Easter is the most important point in comparing the Julian and Gregorian calendars as church calendars. However, this topic, which requires both scientific and theological consideration, is beyond the scope of this article. We only note that the creators of the Orthodox Easter achieved the same goal as the creators of the Julian calendar - the greatest possible simplicity with a reasonable level of accuracy.

Today, many citizens of our country have different attitudes towards the events of the coup. 1917 years. Some consider it positive experience for the state, others negative. In one thing they always agree that with that coup, much has changed, changed forever.
One of these changes was introduced on January 24, 1918 by the Council of People's Commissars, which at that time was the revolutionary government of Russia. A decree was issued on the introduction of the Western calendar in Russia.

This decree, in their opinion, should have contributed to the establishment of closer ties with Western Europe. 1582 year throughout civilized Europe, the Gregorian calendar replaced the Julian calendar, and famous astronomers of that time connived at this.
Since then, the Russian calendar had a slight difference from the Western one in 13 days.

This initiative came from the Pope himself. However, the Russian Orthodox hierarchs were very cool towards their Catholic partners, so for Russia everything remained the same.
So citizens of different countries with different calendars lived for almost three hundred years.
For example, when in western Europe celebrate the New Year, then in Russia it is still only 19 December.
Soviet Russia began to live and count the days in a new way from 1 February 1918 of the year.

By the decree of the Council of People's Commissars (abbreviation of the Council of People's Commissars), which was issued 24 January 1918 year, the day was prescribed 1 February 1918 years to count as 14 February.

It should be noted that the arrival of spring in the central part of Russia has become completely invisible. Nevertheless, it should be admitted that it was not for nothing that our ancestors did not want to change their calendar. 1 March, more reminiscent of mid-February. Surely many paid attention to the fact that the real spring begins to smell only from the middle of March or the first days of it according to the old style.

Needless to say, not everyone liked the new style.


If you think that it was in Russia that were so wild that they did not want to accept the civilized calendar, then you are greatly mistaken. Many countries did not want to accept the Catholic calendar.
For example, in Greece, they began to count according to the new calendar in 1924 year in Turkey 1926 , and in Egypt in 1928 year.
A funny detail should be noted, despite the fact that the Egyptians, Greeks and Turks adopted the Gregorian calendar much later than the Russians, no one noticed them that they were celebrating the Old and New Years.

Even in the stronghold of Western democracy - England and then with great prejudices adopted the new calendar in 1752, Sweden followed this example a year later

What is the Julian calendar?

It is named after its creator Julius Caesar. 46 year B.C. The year had 365 days and began exactly on January 1st The year that was divisible by 4 was called a leap year.
In a leap year, another day was added 29 February.

How does the Gregorian calendar differ from the Julian calendar?

The whole difference between these calendars is that Julius Caesar's calendar, each 4th the year, without exception, is a leap year, and the calendar of Pope Gregory has only those that can be divisible by 4, but not multiples of one hundred.
Although the difference is almost imperceptible, however, after a hundred years, Orthodox Christmas will not be celebrated 7 January as usual, and 8th.

Julian calendar V Ancient Rome from the 7th century BC NS. the lunisolar calendar was used, in which there were 355 days, divided by 12 months. Superstitious Romans were afraid of even numbers, so each month consisted of 29 or 31 days. The New Year began on March 1st.

In order to bring the year as close to the tropical one (365 and ¼ days), once every two years, they began to introduce an additional month - marcedonia (from the Latin "marzes" - payment), equal initially to 20 days. This month, all cash settlements of last year were supposed to end. However, this measure did not manage to eliminate the discrepancy between the Roman and tropical years. Therefore, in the 5th century. BC NS. marzedonia began to be administered twice every four years, alternating with 22 and 23 additional days. Thus, average year in this 4-year cycle it was equal to 366 days and became approximately ¾ days longer than the tropical year. Using their right to enter additional days and months into the calendar, the Roman priests - pontiffs (one of the priestly colleges) confused the calendar so much that in 1 c. BC NS. there is an urgent need for its reform.

This reform was carried out in 46 BC. NS. at the initiative of Julius Caesar. The reformed calendar in his honor became known as the Julian calendar. The Alexandrian astronomer Sozigen was invited to create a new calendar. The reformers were faced with the same task - to bring the Roman year as close as possible to the tropical one and, thanks to this, to maintain constant correspondence of certain days of the calendar to the same seasons.

The Egyptian year of 365 days was taken as a basis, but it was decided to introduce an additional day every four years. Thus, the average year in the 4-year cycle became 365 days and 6 hours. The number of months and their names remained the same, but the length of the months was increased to 30 and 31 days. An additional day was added to February, which had 28 days, and it was inserted between the 23rd and 24th, where marcedonia was previously inserted. As a result, in such an elongated year, the second 24th number appeared, and since the Romans were counting the day in an original way By determining how many days remain until a certain day of each month, this extra day turned out to be the second sixth before the March calendars (before March 1). In Latin, such a day was called "bis sectus" - the second sixth ("bis" - twice, "sixth" - six). In the Slavic pronunciation, this term sounded somewhat differently, and the word "leap year" appeared in the Russian language, and the leap year began to be called a leap year.

In ancient Rome, in addition to calendars, special names had the fifth days of each short (30 day) month or the seventh of the long (31 days) month - Nones and the thirteenths of the short or fifteenth long month - Ides.

January 1 was considered the beginning of the new year, since that day consuls and other Roman magistrates began to fulfill their duties. Subsequently, the names of some months were changed: in 44 BC. NS. quintilis (fifth month) in honor of Julius Caesar began to be called July, in 8 BC. NS. sextilis (sixth month) - August in honor of Emperor Octavian Augustus. Due to the change in the beginning of the year, the ordinal names of some months lost their meaning, for example, the tenth month ("december" - December) became the twelfth.

The new Julian calendar has acquired the following form: January ("Januaris" - named after the two-faced god Janus); February ("februarius" is the month of purification); March ("Martius" - named after the god of war Mars); April ("aprilis" - probably got its name from the word "apricus" - warmed by the sun); may ("mayus" - named after the goddess Maya); June ("Junius" - named after the goddess Juno); July ("Julius" - named after Julius Caesar); August ("Augustus" - named after the Emperor Augustus); September ("september" - the seventh); October ("oktober" - the eighth); November (November is the ninth); December ("december" is the tenth).

So, in the Julian calendar, the year became longer than the tropical year, but by an amount significantly less than the Egyptian year, and was shorter than the tropical year. If the Egyptian year was ahead of the tropical one by one day every four years, then the Julian year lagged behind the tropical one by one day every 128 years.

In 325, the first Ecumenical Council of Nicaea decided to consider this calendar obligatory for all Christian countries. The Julian calendar is at the heart of the calendar system that is now used by most countries in the world.

In practice, the leap year in the Julian calendar is determined by the divisibility of the last two digits of the year designation by four. Years are also leap years in this calendar, the designations of which have the last two digits zeros. For example, among 1900, 1919, 1945 and 1956, the leap years were 1900 and 1956.

Gregorian calendar In the Julian calendar, the average length of a year was 365 days 6 hours, therefore, it was more than a tropical year (365 days 5 hours 48 minutes 46 seconds) by 11 minutes 14 seconds. This difference, accumulating every year, led in 128 years to an error in one day, and in 1280 years already in 10 days. As a result, the vernal equinox (March 21) at the end of the 16th century. it was already on March 11, and this threatened in the future, provided the equinox on March 21 was preserved, by moving the main holiday of the Christian church - Easter from spring to summer. According to church rules, Easter is celebrated on the first Sunday after the spring full moon, which falls between March 21 and April 18. Again the need arose for a reform of the calendar. The Catholic Church carried out a new reform in 1582 under Pope Gregory XIII, after whom the new calendar got its name.

A special commission was created from clergy and astronomers. The author of the project was an Italian scientist - physician, mathematician and astronomer Aloysius Lilio. The reform was supposed to solve two main tasks: firstly, to eliminate the accumulated difference of 10 days between the calendar and tropical years, and secondly, to bring the calendar year as close as possible to the tropical one, so that the difference between them would not be noticeable in the future.

The first problem was solved by the administrative procedure: a special papal bull was ordered to count October 5, 1582, as October 15. Thus, the vernal equinox returned to March 21st.

The second problem was solved by reducing the number of leap years in order to reduce the average length of a year in the Julian calendar. Every 400 years, 3 leap years were thrown out of the calendar, namely those with which the centuries ended, provided that the first two digits of the year are not evenly divisible by four. Thus, 1600 remained a leap year in the new calendar, and 1700, 1800 and 1900. become simple, since 17, 18 and 19 are not evenly divisible by four.

The created new Gregorian calendar has become much more perfect than the Julian one. Each year now lagged behind the tropical one by only 26 seconds, and the discrepancy between them in one day accumulated after 3323 years.

Since different textbooks give different figures characterizing the discrepancy in one day between the Gregorian and tropical years, you can give the corresponding calculations. The day contains 86,400 seconds. The difference between the Julian and tropical calendars of three days accumulates after 384 years and is 259,200 seconds (86,400 * 3 = 259,200). Every 400 years, three days are thrown out of the Gregorian calendar, that is, we can assume that the year in the Gregorian calendar decreases by 648 seconds (259200: 400 = 648) or 10 minutes 48 seconds. The average duration of the Gregorian year is thus 365 days 5 hours 49 minutes 12 seconds (365 days 6 hours - 10 minutes 48 seconds = 365 days 5 hours 48 minutes 12 seconds), which is only 26 seconds longer than the tropical year (365 days 5 hours 49 minutes 12 seconds - 365 days 5 hours 48 minutes 46 seconds = 26 seconds). With such a difference, the discrepancy between the Gregorian calendar and the tropical years in one day will come only after 3323 years, since 86,400: 26 = 3323.

The Gregorian calendar was originally introduced in Italy, France, Spain, Portugal and the Southern Netherlands, then in Poland, Austria, the Catholic lands of Germany and a number of other European countries. In those states where Orthodox Christian church, have been using the Julian calendar for a long time. For example, in Bulgaria a new calendar was introduced only in 1916, in Serbia in 1919. In Russia the Gregorian calendar was introduced in 1918. the difference between the Julian and Gregorian calendars has already reached 13 days, so in 1918 it was prescribed to count the next day after January 31, not February 1, but February 14.

The Russian Orthodox Church uses in liturgical life the Julian calendar (the so-called old style), developed by a group of Alexandrian astronomers led by the famous scientist Sozigen and introduced by Julius Caesar in 45 BC. NS.

After the introduction of the Gregorian calendar in Russia on January 24, 1918, the All-Russian Local Council decided that "during 1918 the Church in her daily life will be guided by the old style."

On March 15, 1918, at a meeting of the Department on Worship, Preaching and the Church, the following decision was made: “In view of the importance of the question of reforming the calendar and the impossibility, from the of all autocephalous Churches, to leave the Julian calendar in its entirety in the Russian Orthodox Church. " In 1948, at the Moscow meeting of Orthodox Churches, it was established that Easter, like all rolling church holidays, should be calculated according to the Alexandrian Easter (Julian calendar), and non-rolling ones - according to the calendar adopted in the local church. According to the Gregorian calendar, Easter is celebrated only by the Finnish Orthodox Church.

Currently, the Julian calendar is used only by a few local Orthodox churches: Jerusalem, Russian, Georgian and Serbian. It is also adhered to by some monasteries and parishes in Europe and the United States, the monasteries of Athos and a number of monophysist churches. However, all Orthodox churches that have adopted the Gregorian calendar, except for Finland, still calculate the day of the celebration of Easter and the holidays, the dates of which depend on the date of Easter, according to the Alexandrian Easter and the Julian calendar.

To calculate rolling dates church holidays the calculation is based on the date of Easter, determined by the lunar calendar.

The accuracy of the Julian calendar is low: every 128 years it accumulates an extra day. Because of this, for example, the Nativity of Christ, initially almost coinciding with winter solstice, is gradually shifting towards spring. For this reason, in 1582 in Catholic countries, the Julian calendar was replaced by a more accurate decree by Pope Gregory XIII. Protestant countries gradually abandoned the Julian calendar.

The difference between the Julian and Gregorian calendars is constantly increasing due to the different rules for determining leap years: in the XIV century it was 8 days, in the XX and XXI centuries- 13, and in the XXII century the gap will be equal to 14 days. Due to the growing change in the difference between the Julian and Gregorian calendars, Orthodox churches using the Julian calendar, starting in 2101, will celebrate Christmas not on January 7 according to the civil (Gregorian) calendar, as in the XX-XXI centuries, but already on January 8, but , for example, since 9001 - already March 1 (new style), although in their liturgical calendar this day will still be marked as December 25 (old style).

For the above reason, one should not confuse the recalculation of the real historical dates of the Julian calendar to the Gregorian calendar style with the recalculation to the new style of the Julian church month dates, in which all the days of the celebrations are fixed as Julian (that is, without taking into account which Gregorian date a particular holiday or memorable day corresponds ). Therefore, to determine the date, for example, of the Nativity of the Virgin in the new style in the 21st century, it is necessary to add 13 by 8 (the Nativity of the Virgin is celebrated according to the Julian calendar on September 8), and in the XXII century already 14 days. The translation to the new style of civil dates is carried out taking into account the century of a specific date. So, for example, the events of the Battle of Poltava took place on June 27, 1709, which, according to the new (Gregorian) style, corresponds to July 8 (the difference between the Julian and Gregorian styles in the 18th century was 11 days), and, for example, the date of the Borodino battle is August 26, 1812 year, and according to the new style it is September 7, since the difference between the Julian and Gregorian styles in the 19th century is already 12 days. Therefore, civil historical events will always be celebrated according to the Gregorian calendar at the time of the year in which they occurred according to the Julian calendar (Battle of Poltava - in June, battle of Borodino- in August, M.V. Lomonosov's birthday - in November, etc.), and the dates of church holidays are shifted forward due to their rigid binding to the Julian calendar, which quite intensively (on a historical scale) accumulates calculation errors (after several millennia The Nativity of Christ will no longer be a winter, but a summer holiday).

For quick and convenient translation of dates between different calendars, it is advisable to use