When To Plant Crops: Moon Calendar or Sun Calendar?

I remember hearing that Cleopatra convinced Julius Caesar to change to a solar calendar. When I researched calendar, I found a reference to the early Egyptians. They noticed that Sirius, the Dog Star, had not been visible for several months. Shortly after it reappeared in the eastern sky just before the sunrise, the annual flooding of the Nile began. The Egyptians based their calendar on this event, and realized that a year had 365 days; twelve months of 30 days each with 5 days added at the end. A year is closer to three hundred sixty-five and a fourth days so eventually the calendar was out of synch with the seasons. However, it was more accurate than the lunar calendars on which many early peoples relied.

This information was quite interesting to me after my unexpectedly seeing Sirius in the early morning sky. My last blog related how brilliant Sirius seemed to me, and my joy at discovering it.

The earliest Roman calendar was probably borrowed from the Greeks. It was later amended to a year that was 355 days long with extra days added. By Julius Caesar’s time, officials had sometimes forgotten to add the extra days, making a calendar that didn’t coincide with the seasons. Julius decided to fix it. He hired mathematicians from Alexandria. Whether Cleopatra influenced the choice of the famous Alexandrian mathematicians, who knows?