What made the Egyptian lunar calendar difficult to use?

Answer 1

The Egyptian lunar calendar was difficult to use primarily because it did not accurately align with the solar year. It was based on the cycles of the moon, specifically the 29.5-day cycle of the appearance of the new moon. However, the solar year is approximately 365.25 days.

Due to this discrepancy, the Egyptian lunar calendar gradually fell out of sync with the solar year. Over a span of several years, the months in the lunar calendar would shift through the seasons. For example, if a religious festival was meant to occur during the harvest time, it might eventually fall in the winter or spring in subsequent years.

Furthermore, the Egyptian lunar calendar consisted of only 12 months, each comprising 29 or 30 days. This meant that it was roughly 10 or 11 days shorter than the solar year. To make up for this shortfall, the Egyptians added an extra month called "the intercalary month" roughly every three years, but this adjustment still did not fully align the lunar calendar with the solar year.

The inconsistencies and misalignment between the lunar calendar and the actual solar year made it challenging for the Egyptians to accurately predict the changing seasons, agriculture cycles, and religious festivals. As a result, they eventually adopted a more accurate solar calendar known as the Egyptian civil calendar, which had 12 months of 30 days each and added an extra five or six epagomenal days at the end of the year to maintain alignment with the solar year.