As you know, the calendar is called the definite system of calculation of significant periods of time, based on the apparent motion of celestial bodies. The phrase "lunar calendar" for hearing the representative of Western civilization sounds a little exotic, with a certain touch of the mysterious East, but the Gregorian calendar is based on the ratio of the lunar and solar calendars, ie by comparing the movements of the moon and sun. So that the lunar calendar is much closer to each one of us than we might think.

But worse than the Moon the Sun?

Lunar calendar is such a calendar system that is based on changing the phases of the moon, that is visible to the naked eye conditions illumination of the celestial body .  Thus, the main unit in the lunar calendar is the synodic month, that is the period of time in which the moon passes all its phases .  Given the slight differences depending on the time of year and, accordingly, the angle of the Earth's axis, the synodic month on average is approximately 29 days and 12 hours .  Thus, the lunar year by some simple arithmetic operation (multiply the length of the synodical month, the number of months, that is, 12) takes on a value of 354 days (355 days in a leap year) .  The essential difference with the duration of the year on the solar calendar because the lunar calendar does not depend on the solar calendar .  There is a reverse situation: a solar calendar is largely based on the moon .  Solar year, based on the complete revolution of the Earth around the sun, is 365 days (366 days in a leap year), but a fractional division, for 12 months, is borrowed from the lunar calendar .  Thus, both the Julian and Gregorian calendars currently in force are "mixed" lunisolar calendar .  In modern conditions fully lunar calendar is used in countries where the dominant and defining the basic aspects of life of religion is Islam .  Chronology of the Islamic lunar calendar is conducted on July 16, 622 (Hijrah), the date of the first migration of Muslims led by the Prophet Muhammad from Mecca to Medina .  Start the day is counted not from midnight, but by the time the sun goes down .  The duration is 29 months or 30 days, the very month, as expected, starts with the appearance in the sky "young" crescent moon .

What you need to know about the lunar calendar

In contrast to the purely astronomical solar or habitual lunisolar calendars lunar calendar contains a number of concepts necessary for its own operation, but not always understood by the uninitiated .  To adequately to perceive lunar calendar, you must familiarize yourself with the basic concepts .  And, first of all, you need familiarity with the phases of the moon, because it is on them, and determine all movement of a celestial body .  In general, the phase of the moon is called the part of the lunar disc, which is visible in the sky, that is illuminated by the sun at the moment .  The key to the lunar calendar is the first phase of the moon, the new moon, that is, when this heavenly body is not illuminated by the sun, it does not reflect light and can not be seen from Earth .  The fact that in this state the sun and the moon are in the same line, because of which closes an Earth satellite luminary .  It is for this point and the end of the lunar month is counted (the Moon "dies") .  The beginning of the month due to the second phase, the so-called neomeniey, that is, the appearance of the new moon after moon as a narrow crescent .  This phenomenon, which occurs not later than three days after the new moon, in ancient times was seen as the "birth" of the moon and is the starting point for the beginning of a new lunar segment .  The third phase is a half moon rising, and fourth, respectively, the full moon - the state of heavenly bodies, in which the Sun is virtually "in front" of the moon and, therefore, covers it completely .  The fifth phase of the moon is called the last quarter, that is, half the aging, moving to the new moon, the moon .

In addition, the need to remember the meaning of the concept "moon day". Moon day (or a moonlit night) is a time period from one to another moonrise. The exception is the first lunar day of each month: the day begins at the moment of the new moon. Moon day have the ability characteristic: since they are calculated by the motion of the moon, it will be greatly differ from each other depending on the time of year and geographical coordinates (due to the displacement axis of rotation of the Earth and the Moon). And especially not the same lunar day for the duration of a calendar for days, consisting of 24 hours.

Alexander Babitsky

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