The Gregorian calendar, also referred to as the Christian calendar or the Western calendar, is the most widely used civil calendar. The calendar was introduced in 1582 and was named after Pope Gregory XIII. The Gregorian calendar is a solar calendar. This implies that it is calendar of which the dates are dependent on the position of the Earth and its revolution around the sun. A regular Gregorian calendar year consists of 365 days. During a leap year there are a total of 366 days. Currently it is customary that the 29th of February is considered a leap day. During a leap year most Roman Catholic churches postpone the February festivities after the 23rd of February by one day.
In the Gregorian calendar there are a total of 12 months. A month either has 28, 30 or 31 days. Moreover, as mentioned above, the month February has a total of 29 days in a leap year. A method to remember which month has a specific number of days is to hold up your two fists with the index knuckle of the left hand against the index knuckle of the right hand. Start counting from January from the little knuckle on the left hand. Count knuckle, space, knuckle space. A knuckle symbolizes a month with 31 days and a space represents a month with 30 days or February. The two index knuckles represent July and August. The method can also be used if you start counting from the right hand’s little knuckle. This mnemonic is a simple method to remember how many days each month has.
As addressed above, a Gregorian calendar has an average of 52 weeks. A week is defined as an interval of seven days. In most part of the world, the first day of the week is Monday and the last day of the week is Sunday. The different names of the week were named after classical planets in different languages. For example, Sunday was named after the Sun and Saturday was named after the planet Saturn.
The Islamic calendar, also known as the Hijri calendar, consists of 12 months a year and a total of 354 or 355 days. The Islamic calendar is a lunar calendar. This means that the calendar is based on cycles of the lunar phases. The Islamic calendar is used in many Muslim countries at the same time as the Gregorian calendar since this is the most commonly used calendar. The Islamic calendar is used by Muslims globally to determine the time of Ramadan, the time of Islamic holidays and festivities and the time to attend Hajj in Mecca in Saudi Arabia. Since the calendar is a purely lunar calendar, the Hijri calendar cannot be used for agricultural purposes. The first day of the week in the Islamic calendar starts on a Sunday, also known as (Yawn) al-Ahad. The first month of the Islamic year is referred to as Muharram. During the month Muharram any form of violence is prohibited. This month is considered to be a sacred month and does not allow for fighting of any kind. The current Islamic year is the year 1437 AH and began in 622 AD. The Islamic calendar finds its origin in the time when Prophet Muhammed emigrated from Mecca to Medina.
The Jewish or Hebrew calendar is the calendar used by Jewish religious observances. The calendar does not only determine the dates for the daily Psalm readings but also determines the dates for the Jewish holidays. The Hebrew calendar is a lunisolar calendar. A lunisolar calendar means that the months are dependent on the lunar months while the years are based on the solar years. The Hebrew calendar includes twelve months of 29 or 30 days. The beginning of each new months is dependent on the appearance of a new moon. Similar to the Islamic week, a week in the Hebrew calendar start on Sunday, or also referred to as Yom Rishon meaning first day. The first month in the Jewish calender is called Nisan. In the Torah this month is called the month of the Aviv. This month is a spring month and has a total of 30 days. Jewish people refer to this month as the month of happiness. The current year according to the Jewish calendar is 5776 AM. AM stands for Anno Mundi and means “from the creation of the world”. The year 5776 AM began according to the Gregorian calendar on the 13th of September 2015 and will end on the 2nd of October 2016.