Origin or Etymology
of the word Calendar
How they got their names
How they got their names
The origin of the word Month
What is a ....
The Gregorian is the Calendar in use today
How did that happen ?
CE - BCE - Y2K
Who Invented This?
What is the meaning?
Origin of the Zero?
Zero between BC and AD?
Sand Candle and more
|What is a ----
Day, AM, PM
Where did the number 60
seconds/minutes come from?
Spring - Summer - Fall
Equation of Time-Sun's Declination.
3500 BC to 2000 AD
Who invented the Calendar ?
The Calendar is a system
for arranging the year into
days, weeks and months.
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.
What is the Origin or Etymology
of the word Calendar
Kalendae or calends
Days of the Week
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
For the History of the:
MONDAY .... Moon's-day.
The second day of the week,
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
WEDNESDAY .... Mercury's-day
From the Roman god of peace and prosperity. Our culture adopted the Teutonic god Wotan
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
FRIDAY .... Venus'-day
Roman goddess of the spring seasons, Greek goddess of love. Our culture adopted the name Frigg, the Scandianavian goddess of Love
SATURDAY .... Saturn's-day
From the planet of the same name.
Months of the Year
The word "month" is derived from the word "moon"
January was named for the Roman God Janus.
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
Named for the Roman festival of purification Februa.
February now has 28 days
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.
March has 31 days.
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.
Named for the goddess Maia, the daughter of Atlas and one of the Pleiades.
Named for the goddess Juno, wife of Jupiter and queen of the heavens and gods.
Named for Julius Caesar in 44 BC.
Named for the Roman Emperor Augustus in 8 BC.
From the Latin word septem meaning seven,
From the Latin word octo meaning eight,
From the Latin word nove meaning nine,
From the Latin word decem meaning ten,
Day - Week - - Month - Year
Sabbath - Sunday - First 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
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.
A Mean Solar day is
For more information on Sidereal Time
For more information on how the new
Sabbath - Sunday - Monday
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".
BC and AD : BCE and CE
Y2K > Year 2000 and The New Century 2001
Where did the ZERO Ø come from ?
(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.
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
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.
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.
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.
Zero History Ø
Therefore it is either 1 BC or 1 AD with no Zero.
The important innovation in the Arabic system was the use of positional notation.
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.
The Gregorian & Julian 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 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
A Solar Year is 365 days
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,
For information on Mean Solar Day