Researched
Calendar
Observing moon, sun and stars yields calendars: sowing, taxes and festivals can be planned.
Open in the interactive tree →Egypt introduced an administrative calendar of 365 days (dated roughly to the 3rd millennium BC), while Mesopotamia used lunar months with leap months. The Julian calendar (46 BC) and the Gregorian calendar (1582) corrected the solar year. Shared timekeeping is a precondition for states, trade and astronomy.
Prerequisites
- Writing~3200 BC
- Number Systems & Place Value~3000-2000 BC
Unlocks
- Sundial & Water Clock~1500 BC
- Mechanical Clock~1300
More in Foundations of Civilization · Antiquity
- Writing~3200 BC
- Weights & Standard Measures~2500 BC
- Alphabet~1800 BC
- Sundial & Water Clock~1500 BC
- Libraries~650 BC
- Philosophy~585 BC
- Plato's Academy387 BC
- Paper~105 AD