The lunar calendar is a time reckoning system based on the duration of the full revolution of the moon around the earth. Our natural satellite is the brightest object in the night sky, and the changing phases of the moon is an interesting and exciting sight.
It is quite natural that many peoples are accustomed to using the lunar calendar. Since ancient times, people have watched how a narrow crescent arises in the sky, how it gradually grows, turns into a full disk, and then decreases and disappears, in order to reappear in a few days. The lunar calendar has always been very simple and intuitive. However, this method of calculating time has several disadvantages. The most significant drawback is that the lunar calendar is in no way connected with the movement of the Earth around the Sun and the resulting seasonal climate changes. Therefore, those peoples who switched to a sedentary lifestyle, engaged in agriculture, gradually stopped using this calendar and replaced it with a solar one. After all, they needed to clearly plan at what time to do specific field work, otherwise they could be left without a crop. A less noticeable drawback is that the Moon, while revolving around the Earth, makes a complete revolution at different times. The minimum duration of the lunar month is 29 days 6 hours and 15 minutes, and the maximum is 29 days 19 hours and 12 minutes. Thus, the average duration of the lunar year is 354, 367 days. That is, there can be either 354 days in the calendar lunar year, or 355 (if this year is a leap year). There was a whole system of so-called leap insertions. It was necessary so that the average length of the calendar year more or less exactly coincided with the length of the lunar year. It was different for different peoples, so there was, for example, the Turkish lunar calendar, the Arab lunar calendar, etc. Another drawback arises from the fact that the first day of the new lunar month is considered neomeny, that is, the appearance of a nascent crescent moon in the rays of the setting Sun. The time of this phenomenon differs depending on the location of the observer, the time of year and the duration of the current lunar month, so it is impossible to keep a lunar calendar created on the basis of observations of the Moon in different places on Earth.
