Proleptic Julian calendar
Encyclopedia
The proleptic Julian calendar is produced by extending the Julian calendar
to dates preceding AD
4 when its quadrennial leap year
stabilized. The leap years actually observed between its official implementation in 45 BC and AD 4 were erratic, see the Julian calendar
article for details.
A calendar obtained by extension earlier in time than its invention or implementation is called the "proleptic" version of the calendar, and thus we obtain the proleptic Julian calendar. Likewise, the proleptic Gregorian calendar
is occasionally used to specify dates before its official introduction
in 1582. Because the Julian calendar was actually used before that time, one must explicitly state that a given date is in the proleptic Gregorian calendar when that is used.
Historians since Bede
have traditionally represented the years preceding AD 1 as "1 BC", "2 BC", etc. Bede and later Latin writers chose not to place the Latin zero, nulla, between BC and AD years. In this system the year 1 BC would be a leap year. To determine an interval in years across the BC/AD boundary, it is more convenient to include a year zero
and represent earlier years as negative. This is the convention used in "astronomical year numbering
". In this system the year 0 is equivalent to 1 BC and is a leap year.
Further considerations involve the fact that the Julian calendar isn't much older than AD 1 itself, so simple addition to year numbers from the Roman pre-Julian calendar (Ab urbe condita
) aren't necessarily direct conversions. The top example is that the year 46 BC, as a result of the Julian reform that initiated the calendar of that name, was allotted 445 days by Julius Caesar
. In years prior to this, the Romans added whole intercalary months in an unsystematized manner. In years between this date and AD 4, the leap day likewise was unsystematic.
Julian calendar
The Julian calendar began in 45 BC as a reform of the Roman calendar by Julius Caesar. It was chosen after consultation with the astronomer Sosigenes of Alexandria and was probably designed to approximate the tropical year .The Julian calendar has a regular year of 365 days divided into 12 months...
to dates preceding AD
Anno Domini
and Before Christ are designations used to label or number years used with the Julian and Gregorian calendars....
4 when its quadrennial leap year
Leap year
A leap year is a year containing one extra day in order to keep the calendar year synchronized with the astronomical or seasonal year...
stabilized. The leap years actually observed between its official implementation in 45 BC and AD 4 were erratic, see the Julian calendar
Julian calendar
The Julian calendar began in 45 BC as a reform of the Roman calendar by Julius Caesar. It was chosen after consultation with the astronomer Sosigenes of Alexandria and was probably designed to approximate the tropical year .The Julian calendar has a regular year of 365 days divided into 12 months...
article for details.
A calendar obtained by extension earlier in time than its invention or implementation is called the "proleptic" version of the calendar, and thus we obtain the proleptic Julian calendar. Likewise, the proleptic Gregorian calendar
Proleptic Gregorian calendar
The proleptic Gregorian calendar is produced by extending the Gregorian calendar backward to dates preceding its official introduction in 1582.-Usage:...
is occasionally used to specify dates before its official introduction
Gregorian calendar
The Gregorian calendar, also known as the Western calendar, or Christian calendar, is the internationally accepted civil calendar. It was introduced by Pope Gregory XIII, after whom the calendar was named, by a decree signed on 24 February 1582, a papal bull known by its opening words Inter...
in 1582. Because the Julian calendar was actually used before that time, one must explicitly state that a given date is in the proleptic Gregorian calendar when that is used.
Historians since Bede
Bede
Bede , also referred to as Saint Bede or the Venerable Bede , was a monk at the Northumbrian monastery of Saint Peter at Monkwearmouth, today part of Sunderland, England, and of its companion monastery, Saint Paul's, in modern Jarrow , both in the Kingdom of Northumbria...
have traditionally represented the years preceding AD 1 as "1 BC", "2 BC", etc. Bede and later Latin writers chose not to place the Latin zero, nulla, between BC and AD years. In this system the year 1 BC would be a leap year. To determine an interval in years across the BC/AD boundary, it is more convenient to include a year zero
Year zero
"Year zero" does not exist in the widely used Gregorian calendar or in its predecessor, the Julian calendar. Under those systems, the year 1 BC is followed by AD 1...
and represent earlier years as negative. This is the convention used in "astronomical year numbering
Astronomical year numbering
Astronomical year numbering is based on AD/CE year numbering, but follows normal decimal integer numbering more strictly. Thus, it has a year 0, the years before that are designated with negative numbers and the years after that are designated with positive numbers...
". In this system the year 0 is equivalent to 1 BC and is a leap year.
Further considerations involve the fact that the Julian calendar isn't much older than AD 1 itself, so simple addition to year numbers from the Roman pre-Julian calendar (Ab urbe condita
Ab urbe condita
Ab urbe condita is Latin for "from the founding of the City ", traditionally set in 753 BC. AUC is a year-numbering system used by some ancient Roman historians to identify particular Roman years...
) aren't necessarily direct conversions. The top example is that the year 46 BC, as a result of the Julian reform that initiated the calendar of that name, was allotted 445 days by Julius Caesar
Julius Caesar
Gaius Julius Caesar was a Roman general and statesman and a distinguished writer of Latin prose. He played a critical role in the gradual transformation of the Roman Republic into the Roman Empire....
. In years prior to this, the Romans added whole intercalary months in an unsystematized manner. In years between this date and AD 4, the leap day likewise was unsystematic.