Topic summary
Lunar cycle
Extracted from the Wikipedia article Lunar phase.
Timekeeping
Although the first formal calendar was created in Mesopotamia about 5,000 years ago, archaeologists have identified methods of timekeeping based on the lunar cycle that go back to prehistoric times. For example, marks in a site in Scotland, dated to 10,000 years ago, are thought to have been a lunisolar calendar. According to the interpretation, this calendar marked both the lunar cycle and the midwinter solstice, showing a recognition that it needed to be recalibrated every year because a lunar year is shorter than the solar year.