ANCIENT CALENDARS :



The ancient Babylonians had a lunisolar calendar of 12 lunar months of 30 days each, and they added extra months when necessary to keep the calendar in line with the seasons of the year. The ancient Egyptians were the first to replace the lunar calendar with a calendar based on the solar year. They measured the solar year as 365 days, divided into 12 months of 30 days each, with 5 extra days at the end. About 238 BC King Ptolemy III ordered that an extra day be added to every fourth year, which was therefore similar to the modern leap year. In ancient Greece a lunisolar calendar was in use, with a year of 354 days. The Greeks were the first to intercalate extra months into the calendar on a scientific basis, adding months at specific intervals in a cycle of solar years.