Calendar

Map of calendars used by countries of the world. In countries where more than one calendar is used there are the colors of both calendars in strips.

The calendar is a systematized account of the passage of time, used for the chronological organization of activities. It is a set of rules or norms that try to make the civil year coincide with the tropical year.

Formerly, many were based on lunar cycles, enduring their use in the Muslim calendar, in the date of various Christian religious holidays and in the use of the week (corresponding to the four talks and the best lunar phases, approximately).

Etymology

The term calendar comes from kalends, a term that designates the first day of the month in the Roman calendar, related to the verb calare 'to call';, which refers to the "call" of the new moon when first seen. The Latin calendarium meant "account book, record", as accounts were settled and debts collected in calendariums of each month. The Latin term was adopted into Old French as calendier and from there into Middle English as calender in the 13th century. The spelling calendar is early modern.

History

The oldest calendar was found on a Mesolithic monument in Aberdeenshire, Scotland by British archaeologists. It is believed to date from around 8,000 BC. C., and measures time from the phases of the Sun and the Moon.

The Egyptian calendar emerged at the beginning of the third millennium BC and is the first known solar calendar in history.

The first year of the Roman era, called the Year of Romulus, had ten or twelve months, depending on the bibliography cited. Censorinus, Plutarch, and others stated that the year originally had twelve months, but more credit must be given to Gracan, Fulvius (Nobilior), Varro, Ovid in various passages of their Fasti (i.27, 43, iii.99, 119, 151), Gelius (Noct. Att. iii.16), Macrobius (Saturn. i.12), Solinus (Polyh. i), Servius (ad Georg. i.43), and others, who held that the first Roman year he was only ten months old.

The beginning of the Roman year was not January, as it is today, but in March, and lasted until December. This is confirmed by the fact of the lighting of the sacred fire in the temple of Vesta, on the first day of the year, the first of March. The ten months of the calendar were called Martius, Aprilis, Maius, Iunius, Quintilis, Sextilis, Septembris, Octobris, Novembris, Decembris. The length of the months was thirty-one days for four of them (Martius, Maius, Quinctilis and Octobris) and thirty days for the others, in such a way that the duration of the months was in successive order: 31, 30; 31, 30; 31, 30, 30; 31, 30, 30; with the total duration of the year of 304 days.

Later, the year of Numa was established, with twelve months and 355 days, created around 700 BC. C. by the second king of Rome, Numa Pompilio. Censorino (c20) recounts that fifty-one days were added to the year of Romulus: “one day was taken from each of the hollow months mentioned above, which then added together made 57 days, of which two months were formed, Ianuarius with 29 days, and Februarius with 28 days. Thus all months were thus full, and contained an odd number of days, except Februarius, which was the only gap, and therefore considered more unlucky than the rest". The year was then as follows: Martius, 31 days; Aprilis, 29 days; Maius, 31 days; Iunius, 29 days; Quinctilis, 31 days; Sextilis, 29 days; Septembris, 29 days; Octobris, 31 days; Novembris, 29 days; Decembris, 29 days; Ianuarius, 29 days; and Februarius, 28 days.

Even in this way, the year was eleven days short with respect to the solar (stationary) year, so Numa Pompilius ordered that a month of 22 days be added to it every second and sixth year and of 23 days every four and eighth, making a cycle of eight years. The intercalary month was called Mercedonius (Plutarch, Numa, 19; Caes. 59). The Roman year was based on lunar cycles and, according to Livio, the relationship with the solar years occurred every 19 years. This cycle was introduced in 432 B.C. C. and, although this knowledge lacked popular use, it was used by the pontiffs for the cults of the gods.

In 45 B.C. C. Julio César commissioned the Alexandrian astronomer Sosigenes to elaborate his calendar. He fixed the length of the year at 365 days and six hours, an astonishingly accurate calculation given the rudimentary instruments of the time, since his margin of error was only 11 minutes and 9 seconds per year, that is, less than one second per day., but in order to avoid complications, it was taken to be 365 days long, adding ten days to the year of 355 days. Censorino wrote the following text about it: “The confusion was finally carried so far that C. César, the Pontifex Maximus, in his third consulate, with Lepidus as a colleague, inserted between November and December two months 67-day intervals, the month of February having already received an intercalation of 23 days, and thus made the whole year consist of 445 days. At the same time he provided against a repetition of similar errors by giving up the intercalary month, and by adapting the year to the solar course. For this, to the 355 days of the previously existing year, he added ten days, which he distributed among the seven months that had 29 days, in such a way that January, Sextilis and December received two each, and the others only one; and these additional days he placed at the end of each month, doubtless wishing not to move the various festivals from those positions in each of the months which they had so long occupied. Thus, in the present calendar, although there are seven months of 31 days, the four months that originally had that number are still distinguishable by having their nones on the fifth day of the month. Lastly, in consideration of the quarter day which he considered to complete the year, he established the rule that, at the end of every four years, a single day should be inserted where the month had been previously inserted, that is, immediately after of the Terminalia; that day is now called the Bisextum.". Bissextum comes from bis-sixth. February 24 was called by the Romans "ante diem sextum Kalendas Martias"; in leap years, the 25th day was called "ante diem bis sextum Kalendas Martias", unlike normal years, when it was named "ante diem quintum Kalendas Martias", giving rise to the term leap year ("bis sextum", twice sixth).

Julius Caesar added a day to July, the month of his birth. Augusto did the same with August. Both days were removed from February, which became 28.^{[citation required]} Given the decrease in this month compared to the others, the added day of leap years it was granted to him.

Julius Caesar set the year to begin on January 1, the day the emperor's officials took office. Due to efforts to conquer Spain, the Romans moved the beginning of the year from the March Kalends to Kalends of January, so that the consuls they elected annually would enjoy a greater number of months to prepare for combat.

The imperfection of the Julian Calendar gave rise to the fact that in the year 1582 Pope Gregory XIII entrusted Luis Lilio and the German Jesuit Christopher Clavius with the reform by which the Gregorian Calendar was created.

This reform had two main aspects. On the one hand, since the spring equinox had been brought forward 10 days, these were suppressed to adjust the cycle of the seasons. This adjustment was carried out on Thursday, October 4, 1582, so the following day was considered Friday, October 15. In addition, to ensure that this result could be maintained in the future, it was agreed that leap years whose last two digits were zeros would not be leap years, except if their first two are divisible by four. Thus, of the years 1600, 1700, 1800, 1900 and 2000, which in the Julian calendar are leap years, in the Gregorian calendar only 1600 and 2000 are leap years, so that three days are deleted every four centuries.

This calendar was gradually adopted by various countries and is currently the most widely used civic calendar in the world.

Gregorian calendar approximations are 1 day out of 3300 years from the tropical year. However, due to the precession of the equinoxes, the error with respect to the vernal equinox is 1 day every 7,700 years.

Calendar types

Calendars in widespread use around the world

• Badí’ Calendar (Bahai Calendar)
• Buddhist Calendar
• Chinese Calendar
• Gregorian Calendar
• Hebrew calendar, related to the Anno Mundi (there is ancient Hebrew calendar and the currently used Jewish calendar, created by Hillel Ilin in 258, put in use since the eleventh century of the Gregorian calendar)
• Hindu calendar (Common Designation of the Indian calendar)
• Muslim calendar
• Persian Calendar
• Holocene calendar, which marks the year 1 as the beginning of human life developed, when man ceases to be nomadic and becomes sedentary.

Religious calendars

• Attic calendar

• Babylonian calendar (Wikipedia article in English, still not equivalent in Spanish)
• Aztec Calendar
• Celtic calendar
• Egyptian calendar
• Hellenic calendar
• Religious calendar
• calendar
• Japanese calendar
• Julian calendar
• Roman calendar
• Mayan calendar

Experimental schedules

• Swedish calendar (1-III-1700-"30-II"-1711) (*)
• French republican calendar (1792-1806)
• Paediaphysical calendar (8-IX-1873)
• Soviet revolutionary calendar (1-X-1929-1940)

(*) February 30 is a fictitious date, although there were years that had this date.

Calendar reform proposals

Since ancient times, the life of societies has been basically organized around two temporal cycles. One is the year, whose duration of approximately 365 days, is given by astronomy and the other, shorter, is the cycle of seven days or week, in whose duration, despite being somewhat longer arbitrary, the most relevant cultures of the contemporary world agree. Two other cycles also used in present-day cultures, although of lesser importance, are the month or lunation and the season or quarter.

Because the number of days in the year varies between 365 and 366, and neither of these two amounts is a multiple of seven (7), the arrangement of days in the calendar varies from year to year. Technically, our Gregorian calendar is a cycle, ordered in a particular way, of 14 different calendars.

This fact, together with the arbitrary length of the months (from 28 to 31 days) has meant that since the century XIX various voices will be raised proposing its reform. Leaving aside those that tried to vary the duration of the weeks, these reforms can be classified according to their response to three questions:

A. What to do with the remaining day (or two days, in the case of a leap year):

(1) The most natural solution, and the one that considered the two great proposals for reform of the centuryXX., (the world calendar and the international fixed calendar), is to add the day or remaining days as a day apart from the week, that is, without being a Monday or a Tuesday or a Sunday. This is usually done after the end of the last month and the leap day is sometimes added in half a year.

This solution met with the opposition of the different religions that would see the millennial cycle of the weeks interrupted in this way, causing the reform proposals of the middle of the century to fail XX.

(2) In the same way that the almost six remaining hours of each year are kept to add one more day every four years, you can save thirty hours, that is, one day and a fourth, and add an extra week every five or six years. This option has as a disadvantage that the dates on which equinoxes and solstices occur suffer a greater variation of year in year. However, it is the solution adopted by some calendars that combine year and week, such as the Christian liturgical calendar or the ISO8061 calendar.

b. How to group the 52 weeks that make up the "body" of the year

It would be convenient for the subdivision of the year into months and quarters to meet three characteristics: that each month contain an integer number of weeks, that each season or quarter of the year contain an integer number of months, and that each month have the same number of days or almost the same. However, it is not possible to build a calendar with these three characteristics simultaneously, and some of them must be given up:

(1) If we renounce that the month has an integer of weeks, we can divide the year into four quarters of 91 days, that is thirteen weeks, and each of these quarters in three months of 31, 30 and 30 days. This is the main idea of the global calendar and is the one that represents a minor change over our current calendar.

(2) If we renounce that each station has an integer number of months, that is to say that the number of months is multiple to four, we can build a calendar with 13 months of 4 weeks each, that is, 28 days. This solution is the basis of the international fixed calendar and was already proposed in the mid-centuryXIX by Auguste Comte. It's the only one that every month has the same structure. On the name that would receive the new month and the place of the year in which it would be intercalated there are a wide range of proposals: "Luna" or "Sol" intercalated between June and July, "Colón" intercalated between November and December, or recover the Roman Mercedonium between February and March.

(3) If we renounce that every month has a duration equal to or at least approximate, we can divide the year in four quarters of thirteen weeks, and each of these quarters in three months of 4 or 5 weeks each, that is 28 or 35 days.

C. The week starts on Sunday or Monday

Although this question is of much less relevance than the previous ones, it is not without controversy. In most European countries and in ISO8061, Monday is considered the first day. For the United States and for the Christian and Jewish religions, the first day is Sunday.

This table summarizes many of the calendar reform proposals:

Other reform proposals do not affect the structure of the year but rather its computation, such as the Holocene Calendar.

Summary of main calendars

The dates

In Spanish, dates have traditionally been expressed in many different ways, including:

• 14-05-2004
• 14-V-2004 (expressing the month in Roman numerals)
• 12 June 2006
• Friday, 12 June 2006
• 12 June of MMVI
• Friday, June 12, MMVI
• 12th day of March A.D. MMVI

In writing, the day and year can be written entirely with letters, although this is not usual. The first day of the month can be written with the ordinal "first" or with the cardinal "one". 34;the twelfth (day) of the month of June two thousand and six" or "the twelfth day of the month of June of the year of Our Lord two thousand and six".

You can replace the hyphen with a forward slash "/". You can also indicate the day of the week, putting the first letter of this followed by the date with the previous possibilities. Example: J-7/4/2011. To indicate Wednesday, the letter "X" (thus differentiating from the "M" of Tuesday) followed by the date with the above possibilities, such as X-11/14/2012, although, if we can use more than one letter, it can also be abbreviated as &# 34;My" or "Wed".

Unless the capital letter is required by the punctuation (at the beginning of the text or after the point), the names of the days of the week, the months and the seasons of the year are written in Spanish with a lower case initial.

The years

Time periods that are equal to several years are called:

In years, the point "." or the comma "," as thousands separator (eg 2011).

Formats

A calendar from the Petaluma and Santa Rosa Railroad

The term calendar applies not only to a particular timekeeping scheme, but also to a specific record or device that displays such a scheme, for example, an agenda in the form of a pocket calendar (or personal organizer), a desktop calendar, a wall calendar, etc.

On a paper calendar, one or two sheets might show a single day, week, month, or year. If a sheet is for a single day, it easily shows the date and day of the week. If a sheet is for several days, it shows a conversion table to go from the day of the week to the date and vice versa. With a special pointer, or by crossing out the past days, you can indicate the current date and day of the week. This is the most common use of the word.

In the US, Sunday is considered the first day of the week, so it appears on the far left, and Saturday, the last day of the week, appears on the far right. In Great Britain, the weekend may appear at the end of the week, so the first day is Monday and the last is Sunday. The American calendar is also used in Great Britain.

It is customary to display the Gregorian calendar in separate monthly grids of seven columns, Monday to Sunday, or Sunday to Saturday depending on which day the week is considered to start - this varies by country, and five to six rows, or rarely, four rows when the month of February contains 28 days in a common year beginning with the first day of the week, with the day of the month numbered in each cell, beginning with 1. The sixth row is sometimes removed by marking 23 /30 and 24/31 together as needed.

When working with weeks rather than months, a continuous format is sometimes more convenient, where no blank cells are inserted to ensure that the first day of a new month starts on a new row.

Gallery

There are many types of calendars, serving a wide variety of uses.

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  A calendar of Soviet days, which shows December 12, 1937 and reminds citizens that it is the day of the elections.

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  A Welsh calendar of saints of the late 15th century.

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  A Soviet calendar, which shows on October 22, 1935, with a daily chess problem for entertainment.

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  A calendar of Ottoman days that shows the same day in various formats and languages: rumi, juliano, Gregorian, Islamic and Hebrew

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  An ancient pin-up calendar

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  A calendar printed on a dodecahedron.

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  A pin-up-style propaganda calendar to urge action against malaria

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  A prayer calendar of the Book of Common Prayer

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  Nudist Calendar

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  Details of an Advent calendar with some open doors