The 365-day calendar
Egypt divides the year into twelve months of thirty days and five spare ones.
- When
- Known to
- ± 200 years
- Era
- Bronze Age, Holocene
The Egyptian civil calendar has 365 days with no leap year, which means it drifts against the solar year by one day every four years and completes a full cycle in 1,460. Its virtue is arithmetic simplicity, and it was used by astronomers for millennia afterwards for exactly that reason. The agricultural year was tracked separately by the heliacal rising of Sirius, which announced the Nile flood.