How was the starting point for the Julian Date system chosen?
Hello…I have a simple question : Why did astronomers chose noon of January 1, of 4731 B.C. as the beginning of their calendar? The Julian Date system begins on Jan. 1, 4713 BC. (Note the year–you’ve transposed the digits in your question.) The Julian Period was proposed by French-Italian astronomer and historian Joseph Justice Scaliger in 1583. It may have been named for his father, Julius Caesar Scaliger, or perhaps it was named after the Julian calendar. In Scaliger’s time, there were no known historical events before 4713 BC, so his calendar would avoid BC/AD or negative dates. He also chose the starting point for a Julian period to be the year when three cycles converge: 1) The solar cycle: The 28 year cycle of the days of the month falling on the different days of the week in the Julian (not Gregorian) calendar. 2) The Metonic or “golden number” cycle: The 19 year cycle of the lunar phases and days of the year. 3) The indiction cycle: a Roman tax cycle of 15 years declared by C
