The True Millennium — and Other “Timely” Questions (Part 2)

The True Millennium — and Other “Timely” Questions (Part 2)

Posted in Teaching Tips

(Researched from the internet)


When the papal bull of February 1582 decreed that 10 days should be dropped from October 1582, so that 15 October should follow immediately after 4 October, and from then on the new Gregorian calendar should be used, Italy, Poland, Portugal and Spain all fell in line with other Catholic countries following shortly after. Protestant countries, however, were reluctant to change, and the Greek orthodox countries didn’t change until the start of this century.

In Bulgaria 31 March 1916 was followed by 14 April. In Russia 31 January 1918 was followed by 14 February. And in Greece the changes didn’t take place until only 73 years ago when 9 March 1924 was followed by 23 March. This whole business is so confusing that sources disagree, some saying it took place in 1916, others in 1920.

Further, the Gregorian calendar was introduced into Turkey on 1 January 1927, replacing the Islamic calendar. It replaced the Chinese calendar in either 1912 or 1929, depending on which authorities you believe.

The Roman calendar?

Remember from Part 1 of this article in the last issue of Keystone, that the Roman calendar was replaced by the Julian calendar in 45 BC, and this was replaced by the Gregorian calendar we use now. That old Roman calendar was such a mess, that much of our so-called “knowledge” about it seems to be little more than guesswork.

Originally, the year started on 1 March and consisted of only 304 days of 10 months (Martius, Aprilis, Maius, Junius, Quintilis, Sextilis, September, October, November, and December). These 304 days were followed by an unnamed and unnumbered winter period. The Roman king Numa Pompilius (c. 715-673 BC, although his historicity is disputed) allegedly introduced February and January (in that order) between December and March, increasing the length of the year to 354 or 355 days. In 450 BC, February was moved to its current position between January and March.

The Romans didn’t number the days sequentially from 1. Instead they had three fixed points in each month:

“Kalendae” (or “Calendae”), which was the first day of the month.

“Idus”, which was the 13th day of January, February, April, June, August, September, November, and December, or the 15th day of March, May, July, or October. (You have heard of the need to “beware the Ides of March”? This was the 15th of March, when Ceasar was assassinated by his “mate” Brutus and friends.)

“Nonae”, which was the 9th day before Idus (counting Idus itself as the first day).

The days between Kalendae and Nonae were called “the 4th day before Nonae”, “the 3rd day before Nonae”, and “the 2nd day before Nonae”. (The first day before Nonae would be Nonae itself.)

Similarly, the days between Nonae and Idus were called “the Xth day before Idus”, and the days after Idus were called “the Xth day before Kalendae (of the next month)”.

Julius Caesar decreed that in leap years the “6th day before Kalendae of March” should be doubled. So in contrast to our present system, in which we introduce an extra date (29 February), the Romans had the same date twice in leap years.

January 1st Not Always New Year Day

When Julius Caesar introduced his calendar in 45 BC, he made 1 January the start of the year. However, the church didn’t like the wild parties that took place at the start of the new year, and in AD 567 the council of Tours declared that having the year start on 1 January was an ancient mistake that should be abolished.

Through the middle ages various New Year dates were used. If an ancient document refers to year X, it may mean any of 7 different periods in our present system:

– 1 March X to 28/29 February X+1

– 1 January X to 31 December X

– 1 January X-1 to 31 December X-1

– 25 March X-1 to 24 March X

– 25 March X to 24 March X+1

– Saturday before Easter X to Friday before Easter X+1

– 25 December X-1 to 24 December X

Choosing the right interpretation of a year number is difficult, so much more as one country might use different systems for religious and civil needs.

The Byzantine Empire used a year starting on 1 September, but they didn’t count years since the birth of Christ. Instead they counted years since the creation of the world, which they dated to 1 September 5509 BC.

Since about 1600 most countries have used 1 January as the first day of the year. Italy and England, however, did not make 1 January official until around 1750.

In England (but not Scotland) three different years were used:

– The historical year, which started on 1 January.

– The liturgical year, which started on the first Sunday in advent.

– The civil year, which from the 7th to the 12th century started on 25 December, from the 12th century until1751 started on 25 March, from 1752 started on 1January.

The Names of the Months

A lot of languages, including English, use month names based on Latin. Their Latin names and meaning are listed below. However, some languages (Czech and Polish, for example) use quite different names.

January: Januarius. Named after the god Janus.

February: Februarius. Named after Februa, the purification festival.

March: Martius. Named after the god Mars.

April: Aprilis. Named either after the goddess Aphrodite or the Latin word “aperire”, to open.

May: Maius. Probably named after the goddess Maia.

June: Junius. Probably named after the goddess Juno.

July: Julius. Named after Julius Caesar in 44 BC. Prior to that time its name was Quintilis from the word “quintus”, fifth, because it was the 5th month in the old Roman calendar.

August: Augustus. Named after emperor Augustus in 8 BC. Prior to that time the name was Sextilis from the word “sextus”, sixth, because it was the 6th month in the old Roman calendar.

September: September. From the word “septem”, seven, because it was the 7th month in the old Roman calendar.

October: October. From the word “octo”, eight, because it was the 8th month in the old Roman calendar.

November: November. From the word “novem”, nine, because it was the 9th month in the old Roman calendar.

December: December. From the word “decem”, ten, because it was the 10th month in the old Roman calendar.

The Correct Way to Write Dates

Different countries have different customs. Most countries use a day-month-year format, such as: 25.12.1998 25/12/1998 25/12-1998 25.XII.1998

In the U.S.A. a month-day-year format is common: 12/25/1998 12-25-1998

International standard IS-8601 mandates a year-month-day format, namely either 1998-12-25 or 19981225.

In all of these systems, the first two digits of the year are frequently omitted: 25.12.98 12/25/98 98-12-25

This confusion leads to misunderstandings. What is 02- 03-04? To most people it is 2 Mar 2004; to an American it is 3 Feb 2004; and to a person using the international standard it would be 4 Mar 2002.

If you want to be sure that people understand you, I recommend that you:

* write the month with letters instead of numbers, and

* write the years as 4-digit numbers.

The Origin of the 7-Day Week

The Christian, the Hebrew, and the Islamic calendars all have a 7-day week.

Digging into the history of the 7-day week is a very complicated matter. Authorities have very different opinions about the history of the week, and they frequently present their speculations as if they were indisputable facts. The only thing some academics seem to know for certain about the origin of the 7-day week is that they know nothing for certain.

The first pages of the Bible explain how God created the world in six days and rested on the seventh. This seventh day became the Jewish day of rest, the sabbath, Saturday.

Extra-biblical locations sometimes mentioned as the birthplace of the 7-day week include: Egypt, Babylon, Persia, and several others. The week was known in Rome before the advent of Christianity.

Names of the Days of the Week

These are closely linked to the language in question. Whereas most languages use the same names for the months (with a few Slavonic languages as notable exceptions), there is great variety in names that various languages use for the days of the week. A few examples will be given here.

Except for the sabbath, Jews simply number their week days.

A related method is partially used in Portuguese and Russian:

The order of the following is: English / Portuguese / Russian / Meaning of Russian name

Mon. / segunda-feira / ponedelnik / After do-nothing day

Tue. / terca-feira / vtornik / Second day

Wed. / quarta-feira / sreda / Center

Thur. / quinta-feira / chetverg / Four

Fri. / sexta-feira / pyatnitsa / Five

Sat. / sabado / subbota / Sabbath

Sun. / domingo / voskresenye / Resurrection

Most Latin-based languages connect each day of the week with one of the seven “planets” of the ancient times: Sun, Moon, Mercury, Venus, Mars, Jupiter, and Saturn. French, for example, uses:

(the order is: English / French / “Planet“)

Monday / lundi / Moon

Tuesday / mardi / Mars

Wednesday / mercredi / Mercury

Thursday / jeudi / Jupiter

Friday / vendredi / Venus

Saturday / samedi / Saturn

Sunday / dimanche / (Sun)

The link with the sun has been broken in French, but Sunday was called “dies solis” (day of the sun) in Latin.

It is interesting to note that also some Asiatic languages (for example, Hindi, Japanese, and Korean) have a similar relationship between the week days and the planets.

English has retained the original planets in the names for Saturday, Sunday, and Monday. For the four other days, however, the names of Anglo-Saxon or Nordic gods have replaced the Roman gods that gave name to the planets. Thus, Tuesday is named after Tiw, Wednesday is named after Woden, Thursday is named after Thor, and Friday is named after Freya.

The planets have given the week days their names following this order:

Moon, Mars, Mercury, Jupiter, Venus, Saturn, Sun

Why this particular order?

One theory goes as follows: If you order the “planets” according to either their presumed distance from Earth (assuming the Earth to be the center of the universe) or their period of revolution around the Earth, you arrive at this order:

Moon, Mercury, Venus, Sun, Mars, Jupiter, Saturn

Now, assign (in reverse order) these planets to the 24 hours of the day:

1=Saturn, 2=Jupiter, 3=Mars, 4=Sun, 5=Venus, 6=Mercury, 7=Moon, 8=Saturn, 9=Jupiter, etc., 23=Jupiter, 24=Mars

Then next day will then continue where the old day left off:

1=Sun, 2=Venus, etc., 23=Venus, 24=Mercury

And the next day will go:

1=Moon, 2=Saturn, etc.

If you look at the planet assigned to the first hour of each day, you will note that the planets come in this order:

Saturn, Sun, Moon, Mars, Mercury, Jupiter, Venus

This is exactly the order of the associated week days. Coincidence? Maybe.

It is hard to say if the 7-day week cycle has ever been broken. Calendar changes and reform have never interrupted the 7-day cycles. It is possible that the week cycles have run uninterrupted since the days of Moses (c. 1400 BC).

Some sources claim that the ancient Jews used a calendar in which an extra Sabbath was occasionally introduced. There is strong Biblical evidence for this, but scholars do not agree.

The Bible clearly makes Saturday (the Sabbath) the last day of the week. Therefore it is common Jewish and Christian practice to regard Sunday as the first day of the week (as is also evident from the Portuguese names for the week days mentioned earlier). However, the fact that, for example, Russian uses the name “second day” for Tuesday, indicates that some nations regard Monday as the first day.

In international standard IS-8601 the International Organization for Standardization (ISO) has decreed that Monday shall be the first day of the week.

Are There Weeks of Different Lengths?

If you define a “week” as a 7-day period, obviously the answer is no. But if you define a “week” as a named interval that is greater than a day and smaller than a month, the answer is yes.

The French Revolutionary calendar used a 10-day “week”. The Maya calendar uses a 13 and a 20-day “week”.

The Soviet Union has used both a 5-day and a 6-day week. In 1929-30 the USSR gradually introduced a 5-day week. Every worker had one day off every week, but there was no fixed day of rest. On 1 September 1931 this was replaced by a 6-day week with a fixed day of rest, falling on the 6th, 12th, 18th, 24th, and 30th day of each month (1 March was used instead of the 30th day of February, and the last day of months with 31 days was considered an extra working day outside the normal 6-day week cycle). A return to the normal 7-day week was decreed on 26 June 1940.

The French Revolutionary Calendar

The French Revolutionary Calendar (or Republican Calendar) was introduced in France on 24 November 1793 and abolished on 1 January 1806. It was used again briefly under the Paris Commune in 1871.

Their year consisted of 365 or 366 days, divided into 12 months of 30 days each, followed by 5 or 6 additional days. The months were:

1. Vendémiaire 7. Germinal

2. Brumaire 8. Floréal

3. Frimaire 9. Prairial

4. Nivôse 10. Messidor

5. Pluviôse 11. Thermidor

6. Ventôse 12. Fructidor

The year was not divided into weeks, instead each month was divided into three “decades” of 10 days, of which the final day was a day of rest. This was an attempt to de-Christianize the calendar, but it was an unpopular move, because now there were 9 work days between each day of rest, whereas the Gregorian Calendar had only 6 work days between each Sunday.

The ten days of each decade were called, respectively, Primidi, Duodi, Tridi, Quartidi, Quintidi, Sextidi, Septidi, Octidi, Nonidi, Decadi.

The 5 or 6 additional days followed the last day of Fructidor and were called:

1. Jour de la vertu (Virtue Day)

2. Jour du genie (Genius Day)

3. Jour du travail (Labour Day)

4. Jour de l’opinion (Reason Day)

5. Jour des recompenses (Rewards Day)

6. Jour de la revolution (Revolution Day) (the leap day)

The Chinese Calendar

Although the People’s Republic of China uses the Gregorian calendar for civil purposes, a special Chinese calendar is used for determining festivals. Various Chinese communities around the world also use this calendar.

The beginnings of the Chinese calendar can be traced back to the 14th century BC. Legend has it that the Emperor Huangdi invented the calendar in 2637 BC. Like the Hebrew calendar it is a combined solar/lunar calendar in that it strives to have its years coincide with the tropical year and its months coincide with the synodic months.

Unlike most other calendars, the Chinese calendar does not count years in an infinite sequence. Instead years have names that are repeated every 60 years.

(Historically, years used to be counted since the accession of an emperor, but this was abolished after the 1911 revolution.)

Within each 60-year cycle, each year is assigned a name consisting of two components. The first component is a “Celestial Stem” (these ten words have no English equivalent):

1. jia 6. ji

2. yi 7. geng

3. bing 8. xin

4. ding 9. ren

5. wu 10. gui

The second component is a “Terrestrial Branch”:

1. zi (rat) 7. wu (horse)

2. chou (ox) 8. wei (sheep)

3. yin (tiger) 9. shen (monkey)

4. mao (hare, rabbit) 10. you (rooster)

5. chen (dragon) 11. xu (dog)

6. si (snake) 12. hai (pig)

Each of the two components is used sequentially. Thus, the 1st year of the 60-year cycle becomes jiazi, the 2nd year is yi-chou, the 3rd year is bing-yin, etc. When we reach the end of a component, we start from the beginning: The 10th year is gui-you, the 11th year is jia-xu (restarting the Celestial Stem), the 12th year is yi-hai, and the 13th year is bing-zi (restarting the Terrestrial Branch). Finally, the 60th year becomes gui-hai.

The current 60-year cycle started on 2 Feb 1984. This means we are now in the year geng-chen, the 17th year in the 78th cycle (since the Chinese calendar began in 2637 B.C.): the year of the dragon.

From Keystone Magazine
March 2000 , Vol. VI No. 2
P O Box 9064
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Phone: (06) 357-4399
Fax: (06) 357-4389
email: craig

The True Millennium Is Well Hidden (Part 1)

The True Millennium Is Well Hidden (Part 1)

Posted in Teaching Tips

(Researched from the internet)


The passionate discussions in some papers as to when the new millennium really started is nothing new. “We have uniformly rejected all letters and declined all discussion upon the question of when the present century ends, as it is one of the most absurd that can engage the public attention, and we are astonished to find it has been the subject of so much dispute, since it appears plain. The present century will not terminate till January 1, 1801, unless it can be made out that 99 are 100… It is a silly, childish discussion, and only exposes the want of brains of those who maintain a contrary opinion to that we have stated — The Times, 26 December 1799.

The Birth of Christ and the Christian Epoch

A count of years from an initial epoch is the most successful way of maintaining a consistent chronology. But it must be tied to a sequence of recorded historical events.

The birth of Christ is the initial epoch of the Christian calendar. We count years from an assumed year of the birth of Christ as determined by Dionysius Exiguus (Denys the Little), a monk and astronomer from Scythia in what is now SW Russia. About AD 530 Dionysius was commissioned by Pope John I to calculate dates of Easter for future observances. Dionysius followed previous precedent by extending an existing table (by Cyrillus) covering the period “228-247” which was on a time scale reckoned from the beginning of the reign of Emperor Diocletian. However, Dionysius did not want his Easter table “to perpetuate the memory of an impious persecutor of the Church, but preferred to count and denote the years from the Incarnation of our Lord Jesus Christ”. To accomplish this he designated the years of his table Anni Domini Nostri Jesu Christi 532-550. Thus, Dionysius’ Anno Domini 532 (AD 532 for short) is equivalent to Anno Diocletiani 248. A correspondence was thereby established between the new Christian Era and an existing system associated with historical records. (By the way, when AD is used it is always before the number. BC always follows the number. This year is AD 2000 not 2000 AD.)

What Dionysius did not do was establish an accurate date for the birth of Christ. In his scheme he believed that Christ was born on the 25th of December of the year preceding the start of the year AD 1. There is no year 0 preceding the year AD 1. Indeed, the concept of counting from zero, rather than one, does not exist in Latin and was introduced into Europe from the Middle East many centuries later. Therefore, Dionysius’ calendar places the birth of Jesus Christ at the end of the year 1 BC. The 2,000th anniversary of Christ’s birth would then be 25 December 2000. However, modern research indicates that Christ was probably born in 6 BC and certainly by 4 BC, when Herod died. So the real 2000th birthday of the Lord Jesus, the real new millennium, probably occurred during the years 1995 to 1997.

When Was the Very First Epoch?

James Ussher was born in Dublin, Ireland, in 1581 and died in England in 1656. He lived through a time of tremendous political and religious upheaval in his native Ireland and in England. Though he was a Puritan in theology, he was a royalist in his steadfastness to the king and the principle of divine right of kings. Invited to participate in the Westminster Assembly, which eventually wrote the Westminster Confession and Catechism, Ussher refused because he thought the assembly itself was illegal.

In his day Ussher was an imminent scholar known to the foremost scholars and statesmen in England. At one time he had possibly the largest collection of books in Western Europe. He eventually donated the collection to Trinity College, Dublin, which his uncle James Ussher helped found. During his lifetime he was widely known as a defender of learning, of the value of books secular and sacred, and a proponent of maintaining an independent identity for Irish Protestant faith. He was appointed Archbishop of Armagh in 1625.

His collected works total seventeen volumes. The most famous of these is his Annals of the Old and New Testament, published in the 1650s, which is a detailed chronology and dating of Biblical history, wherein Ussher said God created the world on the morning of October 23, 4004 B.C. He arrived at this date, in part, by adding the ages of Adam and his descendants found in Genesis 5 and 11. (Refinements by others further pinpointed this to 9 a.m., London time, or midnight in the Garden of Eden.)

This would mean that the world’s 6000th birthday was on October 23, 1997. This is determined because there was no year “0”, but the counting went straight from 1BC to AD1. Thus 4004 + 1997 – 1 = 6000. It is very tempting to think of each set of 1000 years as a day, and the 7th would be our Sabbath day or millennium of rest. If Bishop Ussher’s chronology is correct, and if we can validly assume each 1000 years represents a day, then we entered upon our millennium of rest just over two years ago. This also corresponds with one of the possible “true” years of Jesus’ birth.

Types of Calendar

But keeping track of time and constructing calendars is a very tricky business. The principal astronomical cycles upon which we base time and calendars are:

1) the day (the rotation of the Earth on its axis),

2) the year (the revolution of the Earth around the Sun), and

3) the month (based on the revolution of the Moon around the Earth).

The complexity of calendars arises because these cycles of revolution do not correspond to a number of whole days, but include fractions of days and because astronomical cycles are neither constant nor perfectly commensurable with each other.

We need to identify two kinds of years. The “tropical year” is defined as the mean interval between vernal equinoxes; that is, it is a year that corresponds to the cycle of the seasons and is made up of a certain number of whole days plus a bit left over. This bit left over is not always the same. The other kind of year is a “calendar year”, the kind we are used to seeing on the wall and in diaries. It is made up of either 365 or 366 whole days. You can see that the two kinds of years do not match up exactly.

Three distinct types of calendars have resulted from this situation. (There are about 40 different calendars in use in the world today.)

1) A solar calendar, of which the Gregorian calendar we use today is an example, is designed to maintain synchrony with the tropical year. To do so, days are intercalated (forming leap years) to increase the average length of the calendar year.

2) A lunar calendar, such as the Islamic calendar, follows the lunar phase cycle without regard for the tropical year. Thus the months of the Islamic calendar systematically shift with respect to the months of the Gregorian calendar.

3) The lunisolar calendar has a sequence of months based on the lunar phase cycle; but every few years a whole month is intercalated to bring the calendar back into phase with the tropical year. The Hebrew and Chinese calendars are examples of this type.

The Julian Calendar

It wouldn’t be hard for Dionysius to have made a mistake in determining the date of the birth of Christ, even though both Christ and he lived in times that used the same Julian calendar.

The Julian calendar, introduced by Julius Caesar in 46 BC, was a solar calendar with months of fixed lengths. Every fourth year an intercalary day was added to maintain synchrony between the “calendar year” and the “tropical year”. It served as a standard for European civilization until the Gregorian Reform of 1582.

Julian years are classified as normal years of 365 days and leap years of 366 days. The year is divided into twelve formalized months that were eventually adopted for the Gregorian calendar (the one we use today).

The year 46 BC has been called the “year of confusion”, because in that year Julius Caesar inserted 90 days to bring the months of the Roman calendar back to their traditional place with respect to the seasons. This was Caesar’s first step in replacing a calendar that had gone badly awry. Although the pre-Julian calendar was lunisolar in inspiration, its months no longer followed the lunar phases and its year had lost step with the cycle of seasons. Following the advice of Sosigenes, an Alexandrine astronomer, Caesar created a solar calendar with twelve months of fixed lengths and a provision for an intercalary day to be added every fourth year. As a result, the average length of the Julian calendar year was 365.25 days. This is consistent with the length of the tropical year as it was known at the time.

Following Caesar’s death, the Roman calendrical authorities misapplied the leap-year rule, with the result that every third, rather than every fourth, year was intercalary. Although detailed evidence is lacking, it is generally believed that Emperor Augustus corrected the situation by omitting intercalation (leap years) from the Julian years 9 BC through AD 4. After this the Julian calendar finally began to function as planned.

Through the Middle Ages the use of the Julian calendar evolved and acquired local peculiarities that continue to snare the unwary historian. There were variations in the initial epoch for counting years, the date for beginning the year, and the method of specifying the day of the month. Not only did these vary with time and place, but also with purpose. Different conventions were sometimes used for dating ecclesiastical records, fiscal transactions and personal correspondence.

Caesar designated January 1 as the beginning of the year. However, other conventions flourished at different times and places. The most popular alternatives were March 1, March 25, and December 25. This continues to cause problems for historians, since, for example, February 28, AD 998, as recorded in a city that began its year on March 1, would be the same day as February 28, AD 999, of a city that began the year on January 1.

Days within the month were originally counted from designated division points within the month: Kalends, Nones, and Ides. The Kalends is the first day of the month. The Ides is the thirteenth of the month, except in March, May, July and October, when it is the fifteenth day. The Nones is always eight days before the Ides.

By the eleventh century, consecutive counting of days from the beginning of the month came into use. Local variations continued, however, including counts of days from dates that commemorated local saints. The inauguration and spread of the Gregorian calendar resulted in the adoption of a uniform standard for recording dates.

Gregorian Calendar

The Gregorian calendar resulted from a need to reform the method of calculating dates of Easter. Under the Julian calendar the dating of Easter had become standardized, using March 21 as the date of the equinox. By the thirteenth century it was realized that the true equinox had regressed from March 21 (its supposed date at the time of the Council of Nicea, AD 325) to a date earlier in the month. As a result, Easter was drifting away from its springtime position and was losing its relation with the Jewish Passover. Over the next four centuries, scholars debated the “correct” time for celebrating Easter and the means of regulating this time calendrically. The Church made intermittent attempts to solve the Easter question without reaching a consensus.

By the sixteenth century the equinox had shifted by ten days, so something had to be done. At the behest of the Council of Trent, Pope Pius V introduced some adjustments. Pope Gregory XIII, who succeeded Pope Pius in 1572, soon convened a commission to consider reform of the calendar, since he considered his predecessor’s measures inadequate.

The Gregorian calendar, proposed by Aloysius Lilius, a physician from Naples, met the recommendations of Pope Gregory’s calendar commission and was instituted by the papal bull “Inter Gravissimus”, signed on February 24, 1582. Ten days were deleted from the calendar, so that October 4, 1582 was followed by October 15, 1582, thereby causing the vernal equinox of 1583 and subsequent years to occur about March 21.

This new calendar was promulgated through the Roman Catholic world but took a while considering the logistical problems of communication and governance of those times. Protestant states initially rejected the calendar but gradually accepted it over the coming centuries. (The Gregorian calendar was adopted in Britain 170 years later, in the year 1752, when September 2nd was followed by September 14th. This provides a pretty trap for unwary students of history trying to reconcile events in England with events on the Continent.) As international communications developed, the civil rules of the Gregorian calendar were gradually adopted around the world.

Leap Years

According to the Gregorian calendar, which is the civil calendar in use today, years evenly divisible by 4 are leap years, with the exception of centurial years that are not evenly divisible by 400. Therefore, the years 1700, 1800, 1900 and 2100 are not leap years, but 1600, 2000, and 2400 are leap years.

The Gregorian calendar year is intended to be of the same length as the cycle of the seasons. However, the cycle of the seasons, technically known as the tropical year, is approximately 365.2422 days. Since a calendar year consists of an integral number of whole days, a calendar year cannot exactly match the tropical year. If the calendar year always consisted of 365 days, it would be short of the tropical year by about 0.2422 days every year. Over a century, the calendar and the seasons would become out of sync by about 24 days, so that the beginning of spring in the northern hemisphere would shift from March 20 to April 13.

To synchronize the calendar and tropical years, leap days are periodically added to the calendar, forming leap years. If a leap day is added every fourth year, the average length of the calendar year is 365.25 days. This was the basis of the Julian calendar, introduced by Julius Caesar in 46 B.C. In this case the calendar year is longer than the tropical year by about 0.0078 days. Over a century this difference accumulates to a little over three quarters of a day. From the time of Julius Caesar to the AD 1500s, the beginning of spring shifted from March 23 to March 11.

When Pope Gregory XIII instituted the Gregorian calendar in 1582, the calendar was shifted to make the beginning of spring fall on March 21 and a new system of leap days was introduced. Instead of intercalating a leap day every fourth year, 97 leap days would be introduced every 400 years, according to the rule given above. Thus, the average Gregorian calendar year is 365.2425 days in length. This agrees to within a half a minute of the length of the tropical year. It will take about 3300 years before the Gregorian calendar is as much as one day out of step with the seasons.

The Hebrew Calendar

As mentioned earlier, there are other calendars, most of three types: solar, such as our Gregorian; lunar, such as the Islamic; and lunisolar, such as the Hebrew calendar. It is based on calculation rather than observation. Each year consists of twelve or thirteen months, with months consisting of 29 or 30 days. An intercalary month is introduced in years 3, 6, 8, 11, 14, 17, and 19 in a nineteen-year cycle. Years are counted since the creation of the world, which is assumed to have taken place in 3761 BC. In that year, AM 1 started (AM = Anno Mundi = year of the world). Our 1 January 2000 is in A.M. 5760.

The Islamic Calendar

The Islamic calendar is a purely lunar calendar in which months correspond to the lunar phase cycle. As a result, the twelve lunar months rotate through the four seasons, coming back to where they used to be over a period of about 33 years. That is, their month of Safar sometimes occurs in winter, sometimes in summer.

Day 5 of their week, which is called Jum’a, is the day for congregational prayers. Unlike the Sabbath days of the Christians and Jews, Jum’a is not a day of rest. It begins at sunset on Thursday and ends at sunset on Friday.

Their initial epoch, A.H. 1 (Anno Higerae), is reckoned from the Era of the Hijra, commemorating the migration of the Prophet and his followers from Mecca to Medina. It is generally taken by astronomers to be Thursday, July 15, AD 622 (Julian calendar), while those favouring chronological tables generally use Friday, July 16, AD 622. Our 1 January 2000 is in A.H. 1420.

Keeping Time is a Messy Business

Sweden has a curious history. Sweden decided to make a gradual change from the Julian to the Gregorian calendar. By dropping every leap year from 1700 through 1740 the eleven superfluous days would be omitted and from 1 Mar 1740 they would be in sync with the Gregorian calendar. (But in the meantime they would be in sync with nobody!)

So 1700 (which should have been a leap year in the Julian calendar) was not a leap year in Sweden. However, by mistake 1704 and 1708 became leap years. This left Sweden out of synchronisation with both the Julian and the Gregorian world, so they decided to go “back” to the Julian calendar. In order to do this, they inserted an extra day in 1712, making that year a double leap year! So in 1712, February had 30 days in Sweden.

Later, in 1753, Sweden changed to the Gregorian calendar by dropping 11 days like everyone else.

From Keystone Magazine
January 2000 , Vol. VI No. 1
P O Box 9064
Palmerston North
Phone: (06) 357-4399
Fax: (06) 357-4389
email: craig