The Many Calendar Systems

Even though everyone starts and ends their day the same way, with the sun setting and rising, not everyone keeps track of their day the same way. There are many calendar systems that are used worldwide and are either named according to the country or a certain religion, a few are also just named after its founder or creator. Some of the most common are as follows:

Babylonian Calendar -  Lunisolar

• The Babylonian calendar was introduced during the second millennium BCE and originated in Babylonia (southern Iraq) by Persian Kings.
  
• LEAP YEAR: An leap year or month was inserted if needed; not much information is found on this topic. 
  
• USED: Ancient Mesopotamia
  
• MONTHS: 12
  
• DAYS: 354
  

Egyptian Calendar - Solar

• It is unknown when the Egyptian calendar originated but was said to have been introduced about over 5000 years ago.
  This calendar is a 365-day year calendar, meaning it is solar. 
  
• LEAP YEAR: There aren't any!
  
• USED: Egypt
  
• MONTHS: 12
  
• DAYS: 365
  

Roman Calendar - Lunar

• The original Roman calendar is said to be lunar and, according to the legend, was created by Romulus, who was said to have founded Rome, in about 738 BC. 
  
• There were also 10 months in the original calendar, as they started the calendar year with March (Martius (31 days)), then followed Aprillis (29 days), Maius (31 days), Lunius (29 days), Quintilis (31 days), Sextilis (29 days), September (29 days), October (31 days), November (29 days), December (29 days). And because the calendar was not in sync with the seasons and the earth's revolving around the sun, 2 more months were added, January (Ianurarius (29 days)) and February (Februarius (28 days)). Later on, they added a leap year month (Intercalaris) which would normally be used every 2 or 3 years.
  
• When Julius Caesar became "Pontifex Maxiumus", leap months were eliminated. Resulting in the Julian calendar during the 45 BCE. 
  
• LEAP YEAR: There will be a leap year every four years which adds a day to the end of the month in February. 
  
• USED: Ancient Rome
  
• MONTHS: 12
  
• DAYS: 355
  

Julian Calendar - Solar

• The Julian Calendar originated in 1583 by Julius Caesar.
  
• LEAP YEAR:  An extra day is added to the end of February every 4 years (same as the Gregorian calendar). 
  
• USED: Mount Athos
  
• MONTHS: 12
  
• DAYS: 365-366
  

Gregorian Calendar - Solar

• Originated in October of 1582, by Pope Gregory XIII, as a modification/replacement of the Julian calendar. 
  With the Julian calendar still not entirely accurate, with the equinoxes and how the Earth continued to revolve around the sun, people several years later will discover the calendar "shifting" and then decide to push for reform. 
  
  
• However, even though the Julian calendar didn't work in some parts of the world, people are still able to use it, for example, Mount Athos in Greece uses that particular calendar.
  
• LEAP YEAR:  Every four years is a leap year with an extra day being added at the end of February.
  
• USED: Most of the world
  
• MONTHS: 12
  
• DAYS: 365-366
  

Hebrew Calendar - Lunisolar

• This calendar was created in 3761 BC by Hillel II.
  
• LEAP YEAR: A leap month is added to this calendar every 2 to 3 years, or 7 times in a 19-year period (cycle). 
  
• USED: Israel
  
• MONTHS: 12-13 
  
• DAYS: 353 to 385
  

Buddhist Calendar - Lunisolar

• The Buddhist calendar originated in 544 BC. 
  
• LEAP YEAR: A leap month of 30 days every third year. 
  
• USED: Sri Lanka, Thailand Vietnam, Singapore, Malaysia, Cambodia, Laos, Munmar, and India
  
• MONTHS: 12-13
  
• DAYS: 354-385
  

Islamic Calendar - Lunar

• This calendar originated in July 16, 622 by Caliph Umar I
  
• LEAP YEAR: An extra day is added to the last month of the year. 
  
• USED: Saudi Arabia; Muslim countries will use both the Islamic calendar (for religious reasons) and the Gregorian calendar (for civil reasons). 
  
• MONTHS: 12
  
• DAYS: 354-355
  

Chinese Calendar - Lunisolar

• The Chinese calendar was created in the 14th century
  
• Each Lunar year in Chinese has a zodiac sign animal, there are 12 of these animals. The Rat, the Ox, the Tiger,  the Rabbit, the Dragon, the Snake, the Horse, the Goat, the Monkey, the Rooster, the Dog, and the Pig. Those are all in order and the beginning of the Chinese year, is, of course, Chinese New Year!
  
• To give a little hint as to where they are with the 12 animals here are a few dates. in 2000, it was the year of the Dragon. In 2022, it was the year of the Tiger. In 2023, our current year is the year of the Rabbit.
  
• LEAP YEAR: An extra month gets added approximately every 3 years (or 7 times in 19 years). 
  
• USED: Some East Asian countries such as Korea, Vietnam, Thailand, and Japan as well as Chinese of course!
  
• MONTHS: 12-13
  
• DAYS: 354
  

Many other countries have their own calendars that they use for example; Swedan - Swedish Calendar, Kurdish - Kurdish Calendar, etc.

Subject to edit by the instructor!

That is very interesting. I knew that different countries/religions had different calendars but I didn’t know there were so many. It’s not surprising that the world isn’t “on the same page”. People can’t even agree about what year it is.