Calendar a History www.TimeKeepingSite.org The origin of the first Calendar Who invented the Calendar A history of the Western Calendar Gregorian, Julian and Roman Calendars. How the Days of the Week got their Names How the Months got their Names When was the Zero in use BC and AD Inventor Dionysius Exiguus. Timekeepingsite.org @K6XF

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Who Invented the Calendar Origin or Etymology of the word Calendar .										.	.
.										.	Days How they got their names
Months How they got their names The origin of the word Month .										.	.
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The Gregorian & Julian Calendar The Gregorian is the Calendar in use today Leap Year How did that happen ? .										.	.
.										.	BC - AD CE - BCE - Y2K Who Invented This? What is the meaning? Dionysius Exiguus .
Zero History Ø Origin of the Zero? Zero between BC and AD? .										.	.
.										.	Clock a History Water, Clepsydras Sand Candle and more .
What is a ---- Second, Minute, Hour Day, AM, PM .										.	.
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Solstice & Equinox Spring - Summer - Fall Cross-Quarter Days Sunset-Sunrise Equation of Time-Sun's Declination.										.	Timekeepers Timeline Clock History 3500 BC to 2000 AD .

Who invented the Calendar ? The Calendar is a system for arranging the year into days, weeks and months. Lunar Calendar Historians donot know who or when mankind invented the first calendar, probably early man when he first carved a notch into a stick or a bone which marked the passing of each full moon. Notched bones used to record moon phases have been found in Africa and Europe dating back to about 20,500 BC. What is the Origin or Etymology of the word Calendar Kalendae or calends was the first day of each month in the ancient Roman calendar Middle English and Anglo-French calender . Medieval Latin kalendarium, from the Latin word for accounting books. The Gregorian & Julian Calendar The Gregorian is the Calendar in use today

Days of the Week How they got their names The Babylonians named each of the days after one of the planetary bodies known to them, a custom later adopted by the Romans, which continued with the Julian and Gregorian Calendars. SUNDAY .... Sun's-day. The first day of the week, named for the Sun ..... Sun's-day For the History of the: Sabbath, Sunday and the First Day of the Week GO HERE MONDAY .... Moon's-day. The second day of the week, named for the Moon ..... Moon's-day TUESDAY .... Mars's-day From the Roman warrior god Mars. Our culture adopted the Anglo-Saxon word for the warrior god of the Teutonic mythology Tiu or Tiw ..... Tiw's-day. WEDNESDAY .... Mercury's-day From the Roman god of peace and prosperity. Our culture adopted the Teutonic god Wotan ..... Wotan's-day THURSDAY .... Jupiter's-day From the Roman god of lightning, thunder and the husband of Juno. Our culture adopted the Scandinavian god Thor, known as the thunder-god ..... Thor's-day FRIDAY .... Venus'-day Roman goddess of the spring seasons, Greek goddess of love. Our culture adopted the name Frigg, the Scandianavian goddess of Love ..... Frigg's-day. SATURDAY .... Saturn's-day From the planet of the same name. A Roman god of planting and harvest ..... Saturn's-day. @K6XF @K6XF

Months of the Year How they got their names The word "month" is derived from the word "moon" French: "mois" - German: "Monat" Spanish: "mes" - Italian: "mese" - Latin: "mensis" Greek: "mén" or "mene" meaning moon JANUARY.... Janus Roman God January was named for the Roman God Janus. God of doorways, entrances, gateways, thresholds and beginnings. He has two faces, looking in opposite directions. January was the eleventh month of the year in the ancient Roman calendar, however in the 2nd century BC it became the first month of the year. In the Middle Ages most European countries used the Julian calendar and observed New Year's Day on March 25. The Gregorian calendar came into use in 1582. Roman Catholic countries began to celebrate New Year's Day on January 1st at that time. However, Scotland didnot use the Gregorian calendar until 1600 and Germany, Denmark, and Sweden began in about 1700, England followed in 1752. January now has 31 days FEBRUARY.... Named for the Roman festival of purification Februa. February dates from the time of Rome's founding and had 23 days and it was the last month of the year. In 452 BC February was placed in the second position of the Roman Calendar.with 29 days February now has 28 days or 29 in a leap year. MARCH.... Named for the Roman God Mars, who was the god of war and guardian of the state. Mars was the father of Romulus and Remus. In the Middle Ages most European countries used the Julian calendar and observed New Year's Day on March 25. March has 31 days. APRIL.... From the Roman calendar month of Aprilis. Considered a sacred month for the goddess Venus. April also comes from the Latin word aperire meaning "to open" refering to a spring season, opening of the flowers and leaves. April has 30 days. MAY.... Named for the goddess Maia, the daughter of Atlas and one of the Pleiades. May has 31 days. JUNE.... Named for the goddess Juno, wife of Jupiter and queen of the heavens and gods. June has 30 days. JULY.... Named for Julius Caesar in 44 BC. The month originally had the Roman name of Quintilis. July has 31 days. AUGUST.... Named for the Roman Emperor Augustus in 8 BC. The month was formerly known as Sextilis. August has 31 days. SEPTEMBER.... From the Latin word septem meaning seven, which was the seventh month of the Roman calendar September has 30 days. OCTOBER.... From the Latin word octo meaning eight, which was the eight month of the Roman calendar. October has 31 days. NOVEMBER.... From the Latin word nove meaning nine, which was the nineth month of the Roman calendar. November has 30 days. DECEMBER.... From the Latin word decem meaning ten, which was the tenth month of the Roman calendar. December has 31 days. @K6XF @K6XF

History Day - Week - - Month - Year Sabbath - Sunday - First Day    THE DAY The civil day in ancient cultures was made up of "Watches". The length of the watch varied with the season, and were called seasonal or temporal hours. They were related to the length of the Sun’s time above the horizon. This method was known as far back as 1800 BC and was used until the end of the 13th century AD in Europe. At that time it became inconvenient to use because of the invention of the mechanical clock. The seasonal method was uneven and the mechanical clock had an even 12 hours for day and 12 hours for night. The 12 comes from Babylonian 2 x 12 = 24 (5 x 12 = 60). They did this rather than using the base 10. This is known as the Sumerian Sexagesimal System. based on the number 60. And it has carried to this day. We use 60 SECONDS in a MINUTE 60 minutes in an HOUR. The civil day now begins at midnight local time. However the Julian day still starts at noon. From the 2nd century AD until 1925 astronomers counted days from noon to noon. Primitive tribes used dawn to dawn for a day. The Babylonians, Jews and Greeks counted a day from dawn to sunset and sunset to dawn. The Hindus and Egyptians day began at dawn. The Romans and Teutons began their day at midnight. Today the system used for the calendar is the MEAN SOLAR DAY. Mean Solar Day is the average of a solar day because the length of the day varies slightly during the year as the Earth rotates around the Sun. The orbit of the Earth makes the Sun appear to move eastward each day relative to the Stars. The Solar Day is about 4 minutes longer than the Sidereal Day. A Mean Solar day is 24 hours 3 minutes 56.55 seconds of mean sidereal time. A Sidereal Day is 23 hours 56 minutes 4.1 seconds of mean solar time. For more information on Sidereal Time and Ephemeris Tables Go Here For more information on how the new Atomic Clock keeps today's time: Go Here Sabbath - Sunday - Monday First day of the Week ? SABBATH The seventh day of the week in Hebrew is shabbat or shavat meaning a day of holiness and rest observed by Jews from sunset on Friday to nightfall on the following day, Saturday. (Genesis 2:2) Some Christians observe Saturday as their day of rest and worship. (Mark 2:28) The gradual elevation of Sunday by Christians in place of the Sabbath was further enhanced by opposition to Judaism. The Emperor Constantine, who made his famous civil edict in A.D. 321 that men refrain from working on the first day of the week, Sunday is the "venerable day of the Sun," declared at the Council of Nicaea: "Let us, then, have nothing in common with the Jews, who are our adversaries.... " SUNDAY First day of the week in the USA In AD 321 Emperor Constantine established for the calendar a seven day week and Sunday as the First Day of the Week. Also that Sunday should be a day of rest and worship. Sunday in Christianity is the "Lord’s day" which is a memorial to Jesus Christ’s Resurrection from the dead. Sunday worship dates back to the apostolic times. The author of Revelation writes: "I was in the Spirit of the Lords's day, and heard behind me a great voice, as of a trumpet," (Rev. 1:10) KJV MONDAY There are some countries which have Monday as the first day of the week. This is in accordance with the International Standard "ISO 8601:1988 (E)" Which states under item: 5.4 Combinations of date and time of day representations 3.0 Terms and Definitions 3.17 Week Calendar "A seven day period within a calendar year, starting on Monday and identified by the ordinal number within a year....." There are countries in Europe, such as Denmark, Norway and Sweden that have Monday as the first day of the week. In the USA documents ANSI (X3.30) and NIST (FIPS 4-1) adopted ISO 8601 and list Monday as the first day of the week. However, the calendar in USA has Sunday as the first day of the week. THE WEEK Known as an interval between Market Days. In central Asia five days was used, Egyptians used ten days and the Babylonians like the multiple of seven because of the lunations of the moon. In Rome the eight day cycle was used for market. The origin of the seven day week seems to be related to the four (about) seven day phases of the moon. Also the seven colors in the rainbow, and in the Babylonian times, the seven planets. By the time of the first century BC the Jewish seven-day week seems to have been put into place throughout Rome. The calendar in the USA has Sunday as the first day of the week. The word week comes from Latin "vicis" meaning change. The week is a period of seven days and is now used throughout the world as a division of time. History seems to favor the Hebrew or Chaldean origin and the week is mentioned as a unit of time in the Bible, see the Old Testament book of Genesis 29:27. There are countries in Europe, such as Denmark, Norway and Sweden that have Monday as the first day of the week. In the USA documents ANSI (X3.30) and NIST (FIPS 4-1) adopted ISO 8601 and list Monday as the first day of the week. THE MONTH The Month is taken from the cycles of the Moon phases, which takes about 29.5 days. The Babylonians used 29 and 30 days alternately. The Egyptians used all 30 day months, also the Greeks. The Romans made the Julian calendar on one 28 day month and the others either 30 or 31. January is the first month of the year in the Gregorian calendar with 31 days, and is named for the Roman god Janus, the god of gates, doors, openings and beginnings. January was the 11th month of the year in the ancient Roman calendar, however in the 2nd century BC it became the first month of the year. The month of March is the third month of the Gregorian year in accordance with our present calendar. However, March was the first month of the Roman year and named for Mars the god of war. In England, until the Gregorian calendar was adopted in 1752, March was considered the first month with the legal year beginning on March 25. The month (which is lunar) is notsuitable for determining seasons, it has to be the Sun. The Month is determined in two ways. First, the period taken to complete one orbit of the Earth. Second, the time for the moon to complete a cycle of it phases, called the synodic month and is 29.53059 days, this is the basis of the calendar month. THE YEAR The year is the period for one orbit of the Earth around the Sun. And is measured at the Vernal Equinox (the spring-time) which equals about 365.2 mean solar days which is a tropical year (it varies). If the Synodic months (lunar) are used to count a year, 12 synodic months equal about 354.3 days. This is almost 11 days shorter than the tropical year. And if used it throws the seasons out of sync. Neither tropical (Sun) or synodic (Moon) has a complete number of days. So to compile a calendar that keeps in step with the moon’s phases or with the Sun’s seasons it is necessary to insert days into the calendar which is called "Intercalations". Mean Sidereal time ( Star Time) is about 365.2 with reference to the Stars, one year has past. When the Earth has completed 365.2 rotations with reference to the Sun, one mean solar year has past. Mathematical tables are used to derive mean solar time from mean sidereal time. Neither mean solar nor mean sidereal time is precisely accurate, because the motion of the earth on its axis is not regular. Ephemeris time is used by astronomers for the greatest degree of accuracy. Ephemeris are tables giving the computed positions of celestial bodies for every day of a given period. It is an astronomical almanac containing positional tables. The base position is the vernal equinox. Through the use of mathematical tables, Ephemeris time is converted into mean solar time. Using mean sidereal time the year is: 365 days 6 hours 9 minutes 9.54 seconds. Using mean solar time the year is: 365 days 6 hours 13 minutes 53.1 seconds. A tropical year is: 365 days 5 hours 48 minutes 46.3 seconds The rotation of the earth on its axis, and its tour around the sun, causes the times to vary from year to year, that is the reason for the leap second and the leap year. More @K6XF

LEAP YEAR How did that happen ? In the year 46 BC the calendar was hopelessly confused. So Julius Caesar initiated a reform of the entire system. He appointed the Alexandrian astronomer Sosigenes to undertake the revision of the Calendar. Sosigenes did away with the lunar system and replaced it with the (tropical) solar year of 365.25 days. These changes resulted in the creation of the Julian calendar. Well now, this 365.25 days for the Julian calendar was off a bit, the tropical being 365.242199 days. The difference amounts to 11 minutes and 14 seconds per year. So.. by the year 1572 the calendar was in error by a full 10 days. Pope Gregory III issued a "papal bull" and the Jesuit astronomer Christopher Clavius went to work on this problem. The length of the year was redefined as 365.2422 days a difference of 0.0078 days per year from the Julian calendar. (we now have here a Gregorian calendar). This changed amount of error to 3.12 days every 400 years. Clavius had allowed for such discrepancy and suggested that three out of every four centennial years , which would ordinarily be leap years, should instead be regarded as common years. This lead to the practice that no centennial year could be a leap year unless it was divisible by 400. Following this rule 1700, 1800, and 1900 were common years, but the year 2000 would be a leap year. This Gregorian reform gives us an extremely accurate calendar system. The Gregorian calendar established January 1 as the beginning of the year and has been referred to as the "new style calendar" and the Julian referred to as the "old style calendar". @K6XF

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BC and AD : BCE and CE Y2K > Year 2000 and The New Century 2001 Where did the ZERO Ø come from ? Dionysius Exiguus (Dennis the Little, meaning humble) (c. 470 – c. 540) He was a 6th century Dacian monk born in Scythia Minor, in what is now the territory of Dobruja, Romania. Dionysius Exiguus die-uh-nish-e-us _ egg-zig-u-us Inventor of BC and AD. His invention of BC and AD came about while he was trying to establish the exact day of Easter. Exiguss began his calculation at 753 AUC (ab urbe condita) the years passed since the foundation of the city of Rome, which he believed to be the year of the birth of Jesus Christ from the accounts in the New Testament. BC = Before Christ (Before Jesus Christ’s birth) (Latin = ante Christum) AD = Anno Domini (The year of our Lord) CE = Common Era BCE = Before Common Era The abbreviation CE is a standard way of denoting dates in scholarly literature. The year 1 CE is the same as the year 1 AD and BCE is the same as the year BC The use of BC and AD didnot come into use at the time of Exiguus' invention. It was not until the 10 century that it became in common use. Y2K Chronologers note that No year Zero Ø was used between 1 BC and 1 AD. That results in a century running from 1 through 100 and the next from 101 through 200, a millennium from 1 through 1000 and the next from 1001 through 2000, and so forth. Thus, 2000 is the last year of the 20th century and 2001 will be the first year of the 21st century. Then the "scholars" in 1582 introduced the Gregorian calendar. Now the problem that these western "scholars" encountered was having the vernal equinox and also Easter fall on a date that the church fathers had selected. Therefore dates have been moved in order to meet their requirements and to match the seasonal changes. Also Dionysius Exiguss was not really clear as to when Jesus was born, and as such there are historian that find evidence that he could have been off five or more years. During the Julian and the Gregorian period the calendar has had many intercalation. Even today with the atomic clock, there are leap seconds so as to keep our clock/calendar in sync with the seasons. So the western calendar has gone through many changes. Also at that time period in history "zero" was not in use in Europe. There is no specific moment in history when the use of BC and AD began after its invention by Dionysius Exiguss, which was sometime in the middle of 500 AD. In fact in some areas of the world it did not become into use until the 10th century AD. So it was very slow to be accepted. There are some areas of the world that have never switched totally, they presently use two calendars. They kept their old calendar, such as Jewish, some parts of China, Islam and others. @K6XF

Zero History Ø Therefore it is either 1 BC or 1 AD with no Zero. The first recorded use of the zero in Europe was about 976 AD. In the development of written notation, a symbol for zero was evolved long after symbols for the other numbers were invented. The Babylonians used written symbols for numbers thousands of years before they invented a symbol for zero. Zero was introduced initially, not as a number to be used in computation. In Egypt the zero was used between two numbers to indicate an empty space, never at the end of a number. Mayans did have the zero symbol but their base notation rendered it useless. The important innovation in the Arabic system was the use of positional notation. **The first use of Zero (0) as a place holder in positional base notation was by the Arab, Muhammad ibn Musa al-Kwarizmi, born in Baghdad (c 780-850). Kwarizmi, a muslim mathemathician and astronomer, introduced Hindu-Arabic numerals and his book "Kitab al-jabr wa al-mugabalah" influenced these mathamatical concepts in Europe when it was translated into Latin in the 12th century. In fact the term algebra came from his book..."Kitab al-Jbar....". In India the Hindu word for zero was shunya or sunya meaning void and it was translated by the Arabs as sifr, and in English words means cipher and zero. The Hindu-Arabic numerals, known only to a few European intellectuals in the 9th century AD. But in 1202 Leonardo of Pisa published the "Book of the Abacus". Leonardo explained the Hindu-Arabic system, and as such it began to come into use in Europe. Positional Base Notation and The Zero and The Point and Negative Numbers were not widely used until the 17th century AD. The use of zero as a number and place value and the comma and the point and the separation of parts greater or less than one, which is the modern numbering system, determines the numbers weighted value. The use of zero as a number permits the exact alignment of numbers for calculations and provides a consistent means of representing the numbers. @K6XF

The Gregorian & Julian Calendar Egyptian Calendar The Egyptians may have been the first to develope a solar calendar in about 4200BC. Their days were indicated by number and listed according to their months. A calendar date would be listed as year 1 and the 4th month of inundation, then day 5, and under the name of the Pharaoh at that time. Pope Gregory XIII was born in 1502 and died in 1585. He carried out the reform of the Julian calendar. In 1582 he issued a decree dropping 10 days from the calendar which is now known as the Gregorian Calendar and today it serves as an international standard for civil use. In addition, it regulates the ceremonial cycle of the Christian Churches. In fact, its original purpose was ecclesiastical. However, this calendar still requires intercalation (inserting). There must be a leap day or a leap second at times in order to bring the calendar back into sync with the vernal equinox. Although a variety of other calendars are in use today, they are restricted to particular religions or cultures. Pope Gregory XIII was born Ugo Buoncompagni in Bologna, Italy, he was one of the prominent theologians of the time and was created cardinal by Pius IV in 1564. On the death of Pius V, Gregory was elected pontiff. The Julian Calendar came into being sometime in the first century B.C., Julius Caesar ask the Alexandrian astromomer Sosigenes to advise him on how to reform the calendar. Sosigenes suggestion for a 365.25 days in a solar year was accepted. Julius Caesar directed that this calendar be put into use. The Roman Senate changed the name of the month Quintilis to July (Julius) and the month of Sextilis to August (Augustus). This reformed calendar became known as the Julian Calendar. And January first was the beginning of the New year. However, in AD 567 the Council of Tours abolished January first in favor of March, of which the date varied as to what day was the beginning of the New Year. The Julian Calendar served as a standard for most European countries and America until the Gregorian Reform of 1582 A.D. and beyond. Since the Russians did not change from the Julian Calendar to the Gregorian Calendar until 1918, many European have a birthdate based on the Old Style Calendar. Alaska retained the Old Style Calendar until 1867, when they transferred to the Gregorian Calendar. Today the principles of the Julian calendar continue to be used by chronologists. The Julian calendar is formed by applying the rules of the Julian calendar to times before Caesar's reform. This provides a simple chronological system for correlating other calendars and serves as the basis for the Julian day numbers. Julian to Gregorian Calendar The reason for the reform in 1582 from a Julian to a Gregorian Calendar was because the year of 365.25 days was too long. This error of 11 minutes 14 seconds per year amounted to seven days in 1,000 years. The calendar became increasingly out of phase with the seasons. And by 1545 spring time (vernal equinox), which was determining Easter, had moved 10 days from its proper date!! The Julian Calendar became known as "Old Style" and the Gregorian Calendar became known as the "New Style". Therefore anyone born in Russia before 1918, their birthdate is known as "Old Style". Every 28 years the Gregorian Calendar repeats itself. But, remember that leap years are not always every 4 years. Years that end in 00 are not leap years unless it is a multiple of 400. Therefore 1700, 1800, 1900, and 2100 are not leap years. Non-leap years messes up the repeat cycle, however 2000 was a leap year so the 28-year cycle is good from 1901 through 2099. Go To: Leap Year More about refinements in the Julian and Gregorian Calendar. @K6XF

Sidereal Time Star Time This is another method to measure the rotation of the Earth, rather than a reference to the Sun or to the Moon. The method is known as Sidereal Time, and its reference is to the "fixed" stars. Astronomers use the Sidereal Clock and the Modified or Truncated Julian Day A Solar Year is 365 days 5 hours 48 minutes and 45.5 seconds. Sidereal time ( Star Time) - Whenever the Earth has completed 366.2422 rotations with reference to the Stars, one year has past. When the Earth has completed 365.2422 rotations with reference to the Sun, one year has past. Mathematical tables are used to derive mean solar time from mean sidereal time. Neither mean solar nor mean sidereal time is precisely accurate, because the motion of the earth on its axis is not regular. Ephemeris time is used by astronomers for the greatest degree of accuracy. Ephemeris are tables giving the computed positions of celestial bodies for every day of a given period. It is an astronomical almanac containing positional tables. The base position is the vernal equinox. Through the use of mathematical tables, Ephemeris time is converted into mean solar time. For information on Mean Solar Day Go Here @K6XF