Definition of the Calendar: The Calendar is defined as a system of timekeeping involving an orderly arrangement of the division of time that defines the beginning, length and divisions of years, months, weeks and days. Fact 1 about the invention of the Calendar: The name of the inventor of the Calendar is unknown but it is believed to have been invented in c.3000 by Neolithic man during the Stone Age (3000 - 1800 BC) era of inventions. Fact 2 about the invention of the Calendar: Evidence of a prehistoric calendar was discovered in France when a 30,000 year-old animal bone was found with gouged symbols resembling the phases of the Moon. Fact 3 about the invention of the Ancient Egyptian Calendar: The invention of the Ancient Egyptian Calendar was over 5000 years ago and was originally based on the lunar cycle of 12 months of 365 days. The Egyptians grouped their calendar into three seasons of four months and 120 days each each to coincide with the rise and fall of the waters of the River Nile. The Ancient Egyptian month was divided into three 10-day periods known as decans (or decades) and were known by the names of their principal festivals.
Fact 4 about the invention of the Mesopotamian Calendar: The standard Mesopotamian calendar, used by the Babylonians and Sumerians, was established in the 2nd millennium BC and adopted by the Hebrews, Assyrians and the Persians. The Mesopotamian calendar was primarily lunar and divided into two seasons. The months began with the first sighting of the waxing crescent moon just after sunset on the western horizon. Each month was either 29 or 30 days long, and the year approximately 354 days. Fact 5 about the invention of the Mayan Calendar: The Mayan calendar dates back to the fifth century BCE. The Mayan calendar used cycles to keep track of time. One of the cycles is called the Long Count and the Mayans used this specific count to record significant dates over an extended period hundreds of years into the future. The Mayan Long Count calendar led to the much publicized doomsday and apoplectic theories that impending doom, brought about by a cataclysmic event, would occur on December 21, 2012 and would result in the end of the world. The Mayan apocalypse and the end of the world predication obviously came to nothing. Fact 6 about the invention of the Chinese Calendar: The calendar invented by the Ancient Chinese is extremely complicated and based on a solar-lunar calendar in which the months are set according to the cycles of the Moon, and the years are set according to the solar year. The Chinese calendar was established under the Zhou Dynasty was constantly modified according to observations in astronomy and when a new emperor came into power, the numbering of the year recommenced and began at zero. Fact 7 about the invention of the Athenian Calendar: The Athenian calendar, used primarily in Athens by the Ancient Greeks, actually consisted of three separate calendars - the democratic, agricultural, and festival. The Athenians used the agricultural calendar to manage the farming seasons. The festival calendar, tied to the cycles of the moon, included 12 months, with each month beginning on the new moon. The year began in July with the most important religious festival called the Panathenaia, in honour of the goddess Athena. Other major festivals were held in honor of the pantheon of Greek gods including Zeus, Apollo, Artemis, Dionysus and Poseidon. The democratic calendar was used by Athenian citizens to the administration of Athens and the citizenship of its inhabitants. Fact 8 about the invention of the Julian Calendar: The Roman invention of the Julian calendar was introduced by Julius Caesar, with the assistance of Sosigenes, a skilful astronomer from Alexandria. in 46 BC. Fact 9 about the invention of the Julian Calendar: The Roman months were divided into three parts called the kalends, the nones and the ides. The word 'calendar' derives from the Roman 'kalends'. The Kalends was the first day of the month, the Nones was the day of the half moon and the Ides was the day of the full moon. Fact 10 about the invention of the Julian Calendar: The majority of names of the 12 Roman months were named in honor of the Roman gods and goddesses. The first Roman month was called March from Mars, the God or War. April derived from the Greek Aphrodite, the counterpart of Venus, the goddess of love. May, from Maia, the mother, June from the goddess Juno, January from Janus the god of beginnings. Fact 11 about the invention of the Julian Calendar: The Roman month of July was named after Julius Caesar and the month of August was named in honor of Augustus Caesar.
Fact 12 about the invention of the Julian Calendar: The months of September, October, November, December in the Julian Calendar were named after the number of the month. The month of February (the last month) derived from 'februabatur' when sacrifices were made to atone for the the sin of the whole year. Fact 13 about the invention of the Julian Calendar: The Roman days were named after the planets - Sunday from the Sun, Monday from the Moon, Tuesday from Mars, Wednesday from Mercury, Thursday from Jupiter, Friday from Venus and Saturday from Saturn.
Fact 14 about the invention of the Gregorian Calendar: The Gregorian calendar revised the one implemented by Julius Caesar which had become 10 days out of synchrony with the solar cycle. It was established in year 1582, when Pope Gregory XIII introduced the new version to regulate the date of Easter. The Gregorian calendar had 365 days with an extra day every four years (the leap year) except in years divisible by 100 but not divisible by 400. Fact 15 about the invention of the Gregorian Calendar: The Gregorian calendar is the most widely used calendar in the world today. It is based on a 365-day standard year divided into 12 months of irregular lengths Fact 16 about the invention of the Gregorian Calendar: Nearly every 4 years is a leap year, when one extra, or intercalary, day is added to the calendar on February 29, making the leap year 366 days long. Fact 17 about the invention of the Gregorian Calendar: Eleven of the months in the calendar have either 30 or 31 days, whilst February, has only 28 days during the standard year. Fact 18 about the invention of the Calendar: The introduction of the Gregorian calendar allowed for the realignment with events like the vernal equinox and winter solstice.
Fact 19 about the invention of the Calendar - The Seasons: Understanding the progression of the seasons spring, summer, autumn (fall) and winter in the Northern and Eastern Hemisphere was critical for finding or growing food and was crucial to the calendar. The start of the four seasons are now referred to as the Summer solstice (June 21), the autumn equinox (September 22), the winter solstice (December 21) and the spring, or vernal equinox (March 21). Fact 20 about the invention of the Calendar - The English Names for Days of the Week: The English word Monday derives from the Old English word 'mondaeg' meaning "day of the moon". Many of the Anglo-Saxons worshipped the same gods as the Norse men including Mona the goddess of the moon. Tuesday was named after Tiu, the god of war and justice. Wednesday is named after Woden, aka Odin, the chief of the Norse gods. Thursday is named after Thor, the god of Thunder. Friday is named for Freya, the Norse goddess of love. Saturday retained its roots in the Old Roman name Saturn and Sunday is named in honor of Sunne the goddess of the sun. Fact 21 about the invention of the Calendar - The French Names for Days of the Week: In the French language names of the days of the week follow the Romans. Monday (Lundi) is a variant of 'dies Lunae' meaning "day of the moon". Tuesday (Mardi) derives from Mars, the Roman god of war. Wednesday (Mecredi) is named for Mercury the Messenger of the gods. Thursday (Jeudi) is in honor of Jupiter, or Jove, the chief of the gods. Friday (Vendredi) is named for Venus the goddess of love. Saturday (Samedi) is named in honor of Saturn the god of time and Sunday (Dimanche) from Dominica (Latin), meaning the Day of God. Fact 22 about the invention of the Calendar - The Start of the Week: Monday is deemed the first day of the week according to the international standard ISO 8601, however the United States, Canada, Australia and Japan consider Sunday to be the first day of the week. Fact 23 about the invention of the Calendar - The End of the Week: The Christian or Western world consider Sunday as their day of rest and worship. Jewish people count Saturday, the Sabbath, as the day of rest and worship. Muslims refer to Friday as their day of rest and prayer. Fact 23 about the invention of the Calendar: The invention of the calendar was supplemented with timekeeping devices such as the Clock and the introduction of Daylight Savings Time. | 
