How did the ancient Egyptians develop their calendar system?

The ancient Egyptians developed one of the earliest known calendar systems in human history. The calendar system played a significant role in the daily lives of the ancient Egyptians, as it was used to keep track of the yearly flooding of the Nile River, which was crucial for agriculture and the economy. The ancient Egyptian calendar system was based on a solar calendar that consisted of 365 days, divided into 12 months, each with 30 days, and an additional five days added at the end of the year.

The ancient Egyptians believed that the year was divided into three seasons, based on the cycles of the Nile River: inundation, planting, and harvesting. The first month of the calendar, called Thoth, began with the first day of the inundation season, which occurred when the Nile River overflowed its banks and flooded the surrounding fields, providing fertile soil for planting. The ancient Egyptians celebrated the beginning of the new year on this day, which usually fell in mid-July.

The ancient Egyptian calendar was not fixed, and it needed to be adjusted regularly to account for the slight difference between the solar year and the calendar year. To address this issue, the ancient Egyptians added an extra day to the calendar every four years, similar to the leap year system used in modern times.

The ancient Egyptian calendar system remained in use until the Roman conquest of Egypt in 30 BC, when the Julian calendar was introduced.

Overall, the ancient Egyptians developed their calendar system based on their observation of the natural cycles of the Nile River and the sun, and their system helped them keep track of the important events and activities in their daily lives.