Julian calendar
Calendario juliano (año solar de 365,25 días)
- Date
- 45 BCE · confidence high
- Place
- Rome, Italy (calculation by Sosigenes of Alexandria)
- Credited to
- Julius Caesar, advised by Sosigenes of Alexandria
- People
- 👤 Julio César100 BCE–44 BCE
- Field
- Knowledge & symbols
What it is
A reform replacing the Roman lunisolar calendar, manipulated by the pontiffs, with a fixed 365-day solar year with a leap day every four years, after the 445-day 'year of confusion'. The civil calendar of the West for 1,600 years.
The Egyptian calendar with a 365.25-day year proposed in the Decree of Canopus (238 BCE) was never implemented.
What it led to
- Civil and fiscal synchronisation of the whole Empire without arbitrary intercalation
- The Christian computation of Easter and the liturgical calendar
- Accumulated drift that required the 1582 Gregorian reform
- Today's months, with their names and lengths
Built on
- Lunisolar pit calendarc. 8000 BCE
- Circular enclosure solar observatoryc. 4900 BCE
- Solstitial alignment of megalithic monumentsc. 3300-3000 BCE
- 365-day civil calendarc. 2800 BCE
- Gnomon and graduated sundialc. 560 BCE
- 365-day Egyptian calendar
- Alexandrian astronomy
- Calendar of Numa
Made possible
- Jalali calendar1079
- Gregorian calendar
- Computus
- Christian era of Dionysius Exiguus