CHRONOLOGY
The Christian era Anno Domini (AD) begins with the eighth day.
Alden Mosshammer writes:
"If Dionysius Exiguus meant to number the years from the birth of Christ, rather than the conception, then it is more likely that he considered that event to have occurred on 25 December, seven days before the start of the year that we call AD 1. The consensus of most modern scholars favours that interpretation." (Text)
According to the consensus of most modern scholars, Christ was born in the time before Christ (BC).
The time BC lasts until 1 January AD 1 and according to the consensus of most modern scholars, Christ was born seven days before 1 January AD 1.
Christ was allegedly circumcised on the eighth day. (Lk 1:59)
According to the consensus of most modern scholars, the Christian era Anno Domini begins with the day Christ was circumcised.
Incarnation
Jesus Christ came into the world as the incarnation of Logos.
The incarnation of Logos lasted from the conception of Christ to the ascension of Christ.
The Gospel of John says:
"And Logos became flesh and took up residence among us." (Jn 1:14)
It is in no way certain that the incarnation of Logos actually began in the year immediately before the year AD 1.
The year immediately before the year AD 1 is just the year Dionysius Exiguus has established as the very first year ab incarnatione.
0.0
A year 0 does not exist in the Christian era Anno Domini.
In the Gregorian proleptic calendar ISO 8601, the year 0 [0000] is the year immediately before the year 1 [0001].
We can use the Gregorian proleptic calendar ISO 8601 and count days and years both before and after the beginning of year 0.
The beginning of year 0 is the chronological epoch 0.0 Dies Domini.
Days
During a feast of Passover in Jerusalem, Jesus Christ was crucified on a Friday and he rose from the dead on the third day.
These three paschal days (from the beginning of the Friday he was crucified to the end of the Sunday he rose from the dead) are called Triduum Paschale.
The events during Triduum Paschale took place on three separate days in the cycle of weekdays.
The cycle of weekdays begins with either day 1 or day 0.
Ancient time
In ancient time, the cycle of weekdays begins with day 1. The cycle of weekdays is infinite after the beginning of day 1.
Modern time
In modern time, the cycle of weekdays begins with day 0. The cycle of weekdays is infinite both before and after the beginning of day 0.
Hours
An hour is a part of the day. The length of an hour is either variable or fixed.
Ancient time
In ancient time, the day has 12 hours from sunrise to sunset and the night has 12 hours from sunset to sunrise.
The first hour after sunrise is the first hour of the day and the first hour after sunset is the first hour of the night. It is midday at the sixth hour of the day and midnight at the sixth hour of the night.
Because of the changing seasons, the length of an hour is variable:

Modern time
In modern time, the day has 24 hours from midnight to midnight and the length of an hour is fixed 3600 SI seconds.
Sunday
"Throughout history there have been different choices for beginning the day. The ancient Egyptians began the day at dawn, but the Babylonians and Jews chose sunset. The ancient Romans switched to midnight after first using sunrise to mark the day’s beginning. Sunrise was the most common choice in Western Europe before the general use of clock time." (Text)
In the Gospels, the events during Triduum Paschale are described as a sequence of events. The chronology in the sequence of events during Triduum Paschale depends on whether the day begins at sunrise, at sunset, or at midnight.
From sunrise to sunrise
The figure shows the chronology in the sequence of events during Triduum Paschale, if the day begins at sunrise. To the left are the changing times of the day and at the top are the changing days of the week.
From sunset to sunset
The figure shows the chronology in the sequence of events during Triduum Paschale, if the day begins at sunset. To the left are the changing times of the day and at the top are the changing days of the lunar month. The day from sunrise to sunrise is written in parentheses.
Between the day from sunrise to sunrise and the day from sunset to sunset, the following differences are obvious:
- The last supper and the crucifixion took place on two different days (Thursday and Friday), if the day begins at sunrise, but on the same day (Luna 14), if the day begins at sunset.
- The resurrection and Jn 20:19-23 took place on the same day (Sunday), if the day begins at sunrise, but on two different days (Luna 16 and Luna 17), if the day begins at sunset.
Was the last supper a meal during or before the feast of Passover?
- The three synoptic gospels say that the last supper was a meal during the feast of Passover (Mt 26:17, Mk 14:12, Lk 22:7).
- The Gospel of John says that the last supper was a meal before the feast of Passover (Jn 13:1).
Alden Mosshammer writes:
"Since the lamb was slain on the 14th day before evening and the Passover meal was eaten in the evening of that day, Mark’s account implies that the crucifixion took place on the 15th day of the month. ... John’s account implies that the crucifixion took place on the fourteenth day of the month just before a Passover meal would have been taken in the evening. ... If Pilate had tried and executed Jesus on the 15th day of Nisan, he would have been profaning a Jewish holy day of rest. For this and other reasons, many modern scholars prefer the Johannine account." (Text)
Jack Finegan writes:
"In the Fourth Gospel, on the other hand, we saw that the day must have been reckoned from the preceding midnight, according to what Pliny tells us was official Roman usage." (Text)
In particular two passages in the Gospel of John indicate that according to the Gospel of John, the day begins at midnight:
1)
Mary came to the tomb on "the first day" (Sunday) "while it was still dark" (Jn 20:1). "Dark" means before sunrise. Therefore, the day began not at sunrise, because then it would still be Saturday and not yet Sunday, when Mary came to the tomb "while it was still dark".
Jesus came to the disciples "when it was evening on that day, the first day" (Jn 20:19). "Evening" means after sunset. Therefore, the day began neither at sunset, because after sunset it was still "on that day" (Sunday).
According to the Gospel of John, the day began neither at sunrise nor at sunset. This indicates that according to the Gospel of John, the day begins at midnight.
2)
The Bible says:
"On the first day, on the fourteenth day of the month, in the evening, you will eat unleavened bread until the evening of the twenty-first day of the month. For seven days leaven must not be found in your houses." (Ex 12:18-19)
The Bible says seven days without leaven, from the fourteenth to the twenty-first, but if both the fourteenth and the twenty-first are included, there are eight and not seven days from the fourteenth to the twenty-first (14, 15, 16, 17, 18, 19, 20, 21). Therefore, the Bible distinguishes between the day of preparation (14) and the seven days without leaven (15-21).
The feast of Passover (the day of preparation plus the seven days without leaven) lasted eight days (14, 15, 16, 17, 18, 19, 20, 21).
From midnight to midnight
The figure shows the chronology in the sequence of events during Triduum Paschale, if the day begins at midnight. To the left are the changing times of the day and at the top are the changing days of both the week and the lunar month.
Triduum Paschale began at midnight between Thursday and Friday. The feast of Passover lasted eight days from midnight between Luna 13 and Luna 14, to midnight between Luna 21 and Luna 22. The last supper took place Thursday evening on Luna 13 and was therefore a meal before the feast of Passover (Jn 13:1). This also indicates that according to the Gospel of John, the day begins at midnight.
Week
A week is a period of seven days.
The New Testament establishes the foundations of a new week.
- The old week is the week from sunset Saturday to sunset Saturday. In the old week, Sunday is the first day (post sabbatum).
- The new week is the week from midnight Sunday to midnight Sunday. In the new week, Sunday is the seventh day (post dominicam).
The Eighth Day
The Septuagint says:
"And you yourselves will count from the day following the Sabbath, from the day on which you present the sheaf of the elevated offering, seven full weeks. Up to the next day after the last week you will calculate fifty days." (Lv 23:15-16)
When Jesus came to Jerusalem on Palm Sunday, it was not on the first day in an ordinary week of seven days. Palm Sunday was the first day in an extraordinary week of eight days.
The eighth and last day in the extraordinary week of eight days was The Eighth Day.
The Eighth Day was; (i) the third day in Triduum Paschale, (ii) the eighth and last day in the extraordinary week of eight days, (iii) the first day in the count of fifty days.
The count of fifty days / starting on The Eighth Day up to the next day after the fiftieth day / comprised The Eighth Day plus seven new weeks (1+49=50).
Julian date
The Julian date is a continuous count of days and fractions of days before and after the beginning of the current Julian period.
Alden Mosshammer writes:
"Joseph Scaliger established the foundations of modern scientific historical chronology with the publication in 1583 of his Opus de emendatione temporum." (Text)
In his Opus, Scaliger established the Julian period as a cycle of 7980 Julian years. 7980 is the result of 28x19x15 [28x19x15=7980].
Scaliger writes:
"To avoid any cumulative error due to the long series and interconnection of the epochs, I have devised a period which contains both cycles [28x19=532] and the indictions [15]. I shall call this the Julian Period. For to obtain it I multiplied the great 532-year period of Dionysius Exiguus by 15. [532x15=7980]." (Text)
What Scaliger calls "the great 532-year period" is what Bede the Venerable calls "the great paschal cycle". This is a cycle of 532 Julian years.
532 [0]
Dionysius Exiguus established the foundations of the Christian era Anno Domini with the publication in 525 of a table with paschal dates for 5x19 Julian years.
Dionysius Exiguus writes:
"Because the blessed Cyril began his first cycle in the 153rd year of Diocletian and ended his last cycle in the 247th year of Diocletian, we have to start in the 248th year of this man who was a tyrant rather than an emperor. However, we did not want to preserve the memory of an impious persecutor of Christians in our cycles, but chose rather to mark the times with years from the incarnation [ab incarnatione] of our Lord Jesus Christ". (Text)
Dionysius Exiguus chose to start the count of years ab incarnatione with the year 532.
Bede writes:
"It [the great paschal cycle] takes its beginning from the 532nd year of the Lord’s Incarnation, where Dionysius began his first cycle, and extends up to the year 1063 of this most holy Incarnation." (Text)
Leofranc Holford-Strevens writes:
"Evidently he [Bede] takes it for granted that Dionysius not only understood the principle of the 532-year cycle, but began his first 19-year cycle in year 532 of the Incarnation on that basis". (Tekst)
The 532-year cycle immediately before the 532-year cycle from 532 to 1063 (both years included) is the 532-year cycle 0–531.
A year 0 does not exist in Scaliger's calculation. In Scaliger's calculation of the Julian period, the 532-year cycle immediately before the 532-year cycle from 532 to 1063 is the 532-year cycle from 1 BC to AD 531 (both years included).
Indiction
The cycle of indictions is a cycle of 15 Julian years.
In Scaliger's calculation of the Julian period, the number in the cycle of indictions was 3 in the year 1 BC.
Moon
The lunar cycle is a cycle of 19 Julian years.
Alden Mosshammer writes:
"The frequent complaint that Dionysius Exiguus was unfamiliar with the concept of zero has no basis in the facts. The paschal table of Dionysius begins with a new moon on the day of its conjunction with the sun. In some tables, such a new moon was designated as the 30th day of the Lunar cycle. Dionysius, however, counts it as zero (nulla). The lack of a symbol for 0 in Roman numerals and in the Greek alphabetical system of numbering does not mean that the ancients had no notion of the concept." (Text)
In Scaliger's calculation of the Julian period, the number in the lunar cycle was 1 in the year 1 BC.
Sun
The solar cycle is a cycle of 28 Julian years.
In the solar cycle, the red numbers are leap years (366 days), and the black numbers are ordinary years (365 days). The letters above the numbers are the Sunday letters. A leap year has a double Sunday letter and an ordinary year has a single Sunday letter.
The Sunday letter shows the date of the first Sunday of the year.
Every day of the year has one of the seven lowercase letters in the repeating sequence; a, b, c, d, e, f, g. The first day of the year (01/01) always has the lowercase letter a.
In the solar cycle, the Sunday letter A shows that the date of the first Sunday of the year is 01/01. The Sunday letter G shows that the date of the first Sunday of the year is 07/01.
The leap day every fourth year is always in February. In an ordinary year, all Sundays have the same letter as the Sunday letter, but in a leap year, all Sundays before the leap day have the first of the two letters in the double Sunday letter and all Sundays after the leap day have the second of the two letters in the double Sunday letter.
In the Julian calendar, the year 1 BC was a leap year and the first Sunday of that year was 04/01. Therefore, the year 1 BC had the double Sunday letter DC.
But Scaliger writes:
"The year in which the birth of Christ is commonly held to have fallen [1 BC] had the double Sunday letter DC and was therefore 9 in the Roman solar cycle." (Text)
- The great 532-year period has the double Sunday letter DC in the first year.
- The Julian period has the double Sunday letter GF in the first year.
In Scaliger's calculation of the Julian period, the number in the solar cycle was 9 in the year 1 BC.
Chronological epoch
"The first year of the current Julian period, or that of which the number in each of the three subordinate cycles is 1, was the year 4713 BC, and the noon of the 1st of January of that year, is the chronological epoch." (Text)
The Julian period
The current Julian period
Julian day 0
"The number assigned to a day in this continuous count is the Julian Day Number which is defined to be 0 for the day starting at Greenwich mean noon on 1 January 4713 BC, Julian proleptic calendar." (Text)
ISO 8601
ISO 8601 is an international standard for representation and interchange of date and time.
Date is written in the format: yyyy-mm-dd.
Time is written in the format: hh:mm:ss.
Date and time combined are separated by T: yyyy-mm-ddThh:mm:ss.
ISO 8601:2019 says:
"This document uses the Gregorian calendar for the identification of calendar days (4.2.1). This document allows the identification of calendar years by their year number for years both before and after the introduction of the Gregorian calendar (4.2.1)." (Text)
"Each Gregorian calendar year can be identified by a 4-digit ordinal number beginning with ‘0000’ for year zero (4.3.2)." (Text)
October 1582
The red lines show the introduction of the Gregorian calendar.
At the introduction of the Gregorian calendar, the Gregorian calendar jumps from the fourth of October in the Julian calendar to the fifteenth of October in the Gregorian calendar.
The Gregorian proleptic calendar ISO 8601 applies the leap year rules of the Gregorian calendar in the time both before and after the introduction of the Gregorian calendar.
- In the time after the introduction of the Gregorian calendar, there is no difference between the calendar dates in the Gregorian calendar and the calendar dates in the Gregorian proleptic calendar ISO 8601.
- In the time before the introduction of the Gregorian calendar, there is almost always difference between the calendar dates in the Julian calendar and the calendar dates in the Gregorian proleptic calendar ISO 8601.
Only in the period between 0200-03-01 and 0300-02-28 (both days included) there is no difference between the calendar dates in the Julian calendar and the calendar dates in the Gregorian proleptic calendar ISO 8601.
Year 0
A year 0 [0000] does exist in the Gregorian proleptic calendar ISO 8601, but not in the Christian era Anno Domini.
Dies Domini
Dies Domini is a supplement to the Gregorian proleptic calendar ISO 8601.
As a supplement to the Gregorian proleptic calendar ISO 8601, Dies Domini is a continuous count of weekdays and fractions of weekdays before and after the chronological epoch 0.0 Dies Domini.
The chronological epoch 0.0 Dies Domini is the same date and time as 0000-01-01T00:00:00.
The epoch day Dies Domini 0 is the same Saturday as 0000-01-01.
Date
Date and time
New Year
The annual celebration of New Year can be seen as an eight-day festivity (NEW YEAR), where both the first day of the festivity (12-25) and the last day of the festivity (01-01) is a holiday.
12-25
12-25 is X-day (ΧΡΙΣΤΌΣ/CHRISTOS-day).
"And Logos became flesh and took up residence among us, and we saw his glory, glory as of the one and only from the Father, full of grace and truth. John testified about him and cried out, saying, “This one was he about whom I said: The one who comes after me is ahead of me, because he existed before me.” For from his fullness we have all received, and grace after grace. For the law was given through Moses; grace and truth came about through Jesus Christ." (Jn 1:14-17)
01-01
01-01 is New Year's Day and anniversary of the epoch day 0000-01-01.
01-01 begins midnight (00:00:00) between 12-31 and 01-01.
A new millennium begins 00:00:00 between y999-12-31 and y000-01-01.