Muslim calendar

Registration of the age of a library, in A.D. (Anno Dóminithe Christian era and A.H. (Anno Hegiraeyears from the Hegira

The Muslim calendar or Islamic calendar (in Arabic, التقويم الهجري‎ - al-taqwīm al-hijrī) is a lunar calendar consisting of 12 lunar months in a year of 354 or 355 days. It is used to determine the appropriate days of Islamic festivals and rituals, such as the annual fasting period and the appropriate time for the Hajj (pilgrimage to Mecca). In almost all countries where the predominant religion is Islam, the civil calendar is the Gregorian calendar, with Syriac month names used in the Levant and Mesopotamia (Iraq, Syria, Jordan, Lebanon, and Palestine), but the religious calendar is the Muslim.

It begins in the year 622 of the Gregorian calendar and the Julian calendar, the year in which Muhammad, the prophet of Islam, had to flee from the city of Mecca to Medina (Hegira), due to the persecution of his adversaries.

For July 30, 2022, the Islamic year is 1444 AH. In the Gregorian calendar calculation, 1444 AH goes from approximately July 30, 2022 to July 18, 2023.

Features

The Muslim calendar is based on 30-year lunar cycles (360 lunations, Sumerian tradition). The 30-year cycle is divided into 19 years of 354 days and 11 years of 355 days. Years of 354 days are called simple years and are divided into six months of 30 days and another six months of 29 days. The years of 355 days are called intercalary and are divided into seven months of 30 days and another five of 29 days. Years and months alternate. That is, every 33 Muslim years is equivalent to 32 Gregorian years. Intercalations are made by adding a day to the end of the month of du l-hijjah in the 2nd, 5th, 7th, 10th, 13th, 16th, 18th, 21st years, 24th, 26th and 29th of each 30-year cycle.

The origin of this calendar is the day of the beginning of the Hegira, which is 1 A.H. (Anno Hegirae). In the Gregorian calendar it would correspond to July 16, 622.

October 25, 2014, coincided with Muharram 1, the first day of the Hegirian year 1398, whose last day of du l-hijjah 30 coincided with October 24, 2015.

On October 10, 2021 AD, the Islamic year begins 1443 AH.

Currently, in Muslim countries, the Gregorian and Muslim calendars coexist (in Iran and Afghanistan, the Persian calendar). The Islamic date corresponding to the Gregorian can be calculated to within one day by multiplying the Muslim year by 0.970224 and adding 621.5774.

The days of the week

There are seven days of the week:

• al-ahad(الأحد «the first»), Sunday
• al-ithnáyn (الونين «the second»), Monday
• al-tlat (الثلاثاء «the third»), Tuesday
• al-arba’a (الأربعاء «the fourth»), Wednesday
• al-jmís (الميس « el quinta»), Thursday
• al-yumua’a (الجمعة «the meeting»), Friday. This is called because it is the festive day, where collective prayer is made in mosques.
• al-sabt (السبت « el sbt»), Saturday.

The months

The months are 12:

1. Muharram
2. Safar
3. Rabi' al-Awal
4. Rabi' al-Thani
5. Yumada al-Awal
6. Yumada al-Thani
7. Rayab
8. Sha'ban
9. Ramadan
10. Shawwal
11. Dhu ul-Qádah
12. Dhu ul-hyyah

Particularities

The Muslim day begins at sundown, and the month begins about two days after the new moon, when the lunar crescent begins to show.

If we consider the difference in days between the lunar and solar calendars, and the fact that it starts in the year 622, the difficulty of establishing a correspondence between the Muslim and Gregorian calendars becomes evident. There are year correspondence tables, but for a quick and exact calculation the following formulas are used:

• To pass from the Muslim year to the Gregorian:

(1)G=3233H+622{displaystyle G={frac {32}{33}}H+622}

• To pass from the Gregorian year to the Muslim:

(2)H=3332(G− − 622){displaystyle H={frac {33}{32}}(G-622)}}

Where:

G = Gregorian year

H = Muslim year (hergy)

These formulas are used to establish the correspondence between Muslim and Gregorian years, but establishing the exact correspondence of a specific date is almost impossible, and even historians admit an error of a day or so. The cause of this lag is that the beginning and end of each month are regulated according to the observable lunar cycle, which leads to introducing an extra day when the observations do not coincide with the theoretical calculation.

Astronomical Considerations

Because the Islamic calendar relies on certain variable methods of observation to determine its month start dates, these dates sometimes vary slightly from the astronomical lunar calendar month start dates[which...], which are directly based on astronomical calculations. However, the Islamic calendar rarely varies by more than three days from, and approximates, the lunar-astronomical calendar system. Both the Islamic and the astronomical-lunar calendars do not take into account the solar year in their calculations, so these two strictly lunar calendar systems cannot calculate the time of the four seasons of the year.

In the lunar-astronomical calendar system, a year of 12 lunar months has 354.37 days. In this calendar system, the lunar months begin precisely at the time of the "conjunction" monthly, when the Moon is most directly between the Earth and the Sun. The month is defined as the average duration of one revolution of the Moon around the Earth (29.53 days). By convention, the months of 30 and 29 days follow one another, adding up to 59 full days in two successive months. This leaves only a small monthly variation of 44 minutes, which adds up to a total of 24 hours (ie the equivalent of a full day) in 2.73 years. To adjust the accounts, it is enough to add one day every three years to the lunar calendar, in the same way that one day is added to the Gregorian calendar every four years. The technical details of the adjustment are described in the Tabular Islamic Calendar.

The Islamic calendar, however, relies on a different set of conventions for determining the start dates of the months. Each month still has 29 or 30 days, but due to the variable method of observations used, there are no there is usually a discernible order in the sequence of the 29- or 30-day months. Traditionally, the first day of every month is the day (starting at sunset) of the first sighting of the hilal (crescent moon) shortly after sunset. If the hilal is not observed immediately after the 29th day of a month (either because clouds obscure its view or because the western sky is still too bright when the moon sets), then the day beginning with that sunset is on the 30th. This sighting must be carried out by one or more trusted men testifying before a committee of Muslim leaders. Determining the most probable day on which hilal could be observed was one of the motivations for Muslim interest in astronomy, placing Islam at the forefront of that science for many centuries. However, because both lunar reckoning systems are ultimately based on the lunar cycle itself, both systems still roughly correspond to each other, and are never more than three days out of sync with each other.

Clerics watch the moon.

This traditional practice for determining the start date of the month is still followed in the vast majority of Muslim countries. Each Islamic state conducts its own monthly observation of the new moon (or, failing that, waits for the 30 days to expire) before declaring the start of a new month on its territory. However, the lunar crescent only becomes visible about 17 hours after the conjunction, and only subject to the existence of a series of favorable conditions related to climate, weather, geographic location, as well as various astronomical parameters[36]. Since the moon sets progressively later than the sun as you go west, with a corresponding increase in its "age" since the conjunction, western Muslim countries can, under favorable conditions, observe the new moon one day earlier than eastern Muslim countries. Due to the interaction of all these factors, the beginning of each month differs from one Muslim country to another, during the 48-hour period that follows the conjunction. The information provided by the calendar in any country does not go beyond the current month.

Several Muslim countries try to overcome some of these difficulties by applying different rules related to astronomy to determine the beginning of the months. Thus, Malaysia, Indonesia and a few others start each month at sunset on the first day the moon sets after the sun (moonset after sunset). In Egypt, the month begins at sunset on the first day the moon sets at least five minutes after the sun. A detailed analysis of the available data shows, however, that there are large discrepancies between what countries say they are doing on this issue and what they actually do. In some cases, what a country says it does is impossible.