What is a calendar
It is customary to call a calendar system a long time frame with subdivisions into separate shorter periods( years, months, weeks, days).The very word "calendar" came from the Latin words "salo" - to proclaim and "calendarium" - a debt book. The first reminds us that in Ancient Rome the beginning of each month was proclaimed separately, the second - that on the first day of the month it was decided to pay interest on debts.
The need to measure time arose in people already in ancient times - and certain methods of counting time, the first calendars arose many millennia ago, at the dawn of human civilization.
In the fact that time flows, we are convinced, watching the movement, the development of surrounding material bodies. Measure the same time intervals was possible, comparing them with phenomena that are repeated periodically. There are several such periodic phenomena in the world around us. This is primarily a change of day and night, which gave people a natural unit of time - a day, then a change in the phases of the moon, which takes place during the so-called synodic month( from the Greek "synodos" - rapprochement, meant the monthly convergence of the moon and the sun in the sky, This sometimes the moon "finds" on the Sun - there is a solar eclipse), and finally, the change of seasons and the corresponding unit of account - the tropical year( from the Greek "tropos" - turn: the tropical year - the time interval after which the height of the Sunhell horizon at noon, reaching the highest value, again decreases).
To use these units of time, people of antiquity had to realize them, then learn how to count how many times in a certain period of time, dividing the events of interest, one or another account unit was stacked. Without this, people simply could not live, communicateamong themselves, to trade, engage in farming, etc. At first, such a time account could be very primitive. But in the future, as the development of human culture, with increasing practical needs of people calendars are increasingly improved, as the components of their elements appeared the year, month, week.
The difficulties encountered in the development of the calendar are due to the fact that the duration of the day, the synodic month and the tropical year are incommensurable. It is not surprising, therefore, that in the distant past, each tribe, every city, state created their own calendars, varying in number from months to years. In some places people considered time to be units close to the duration of the synodic month, taking in the year a certain( for example, twelve) number of months and not reckoning with the change of the season. So the lunar calendars appeared. Others measured the time by the same months, but the duration of the year was sought to align with the changes of the seasons( the lunisolar calendar).Finally, the third for the account of the days took the change of the seasons, and the phases of the moon were not taken into account at all( the solar calendar).
Thus, the task of building a calendar consists of two parts.
Firstly, on the basis of years of astronomical observations, it was necessary to establish as precisely as possible the duration of the periodic process( the tropical year, the synodic month), which is taken as the basis of the calendar.
Secondly, it was necessary to select the calendar units of the account for whole( !) Days, months, years of different duration and establish the rules for their alternation in such a way that for fairly long intervals the average duration of the calendar year( and also the calendar month in the lunar and lunar-solar calendars) was close to the tropical year( respectively - the synodic month).
Unfortunately, sometimes these two completely different sides of the problem are mixed. So, for example, you can meet the claim that the Mayan calendar was more accurate than ours. This conclusion is made on the grounds that Mayan astronomers have established the duration of the tropical year more accurately than it is adopted in our modern calendar. Meanwhile, considering the merits of this or that calendar, one should speak about its system of leap years, that is, how the compilers of the calendar succeeded, alternating in a certain order calendar years having different duration( different number of days), to approximate the average duration of the calendar yearto the tropical year. If we look at the Mayan calendar from this point of view, then, according to all available data, we have to state that it was significantly worse than ours, since there is no definite evidence that the Maya had any rules for the introduction of leap years.
In their practical activities, people could not do without a certain era-system of account( chronology).In the distant past, each tribe, each settlement created its own calendar system and its era. At the same time, in some places the account of years was conducted from some real event( for example, from the coming to power of one or another ruler, from a devastating war, flood or earthquake), in others - from an event of a fictional, mythical, often associated with religious notions. The starting point of this or that era is usually called its epoch.
Years and millennia passed. In one or other place on the globe, powerful states emerged, often becoming bright foci of culture, centers of civilization that could not only create certain material and spiritual values, but in a sense also perpetuate them, in particular, inscriptions and drawings on tombs, on stone pillars, clay tablets and papyrus or leather, scrolls. Over the past 200 years, historians and archaeologists have made great efforts to find traces of long-forgotten peoples, to study the features of their life, to restore the lost pages of their history. The world was surprised to learn about the high achievements of science and culture of Sumerians, Akkadians, Assyrians, Babylonians and Persians, ancient Chinese and Egyptians, Greeks and Incas, Aztecs and Maya. Cuneiform characters and hieroglyphs have told us about this long forgotten languages.
All these testimonies about the events of the past days had to be streamlined, to find their respective place on the pages of a single world history. Thus the science arose chronology( from the Greek words "chronos" - time and "logos" - the word, the doctrine), whose task is to study all forms and methods of calculating time, to compare and determine the exact dates of various historical events and documents, and more broadly- to know the age of the remains of material culture found during archeological excavations, as well as the age of our planet as a whole.
Needless to emphasize that the mentioned tasks are solved with great difficulty and not at once and that therefore the chronology itself is a very complex field of science. One of the indispensable conditions for success in this field is the knowledge of languages - ancient and new. In addition, chronology is such a scientific field in which astronomy is in touch with history. Therefore, the ideal chronologist will be that scientist who is equally strong both as an astronomer and as a historian. A specialist in chronology must thoroughly understand the astronomical foundations of the calendar( the laws governing the motion of the moon, the conditions for the onset of solar and lunar eclipses, the determination of the possibility of observing them at a specific point on the globe) and to know in advance the materials already available on the history of the countries and peoples of interest to them, their culture,by their calendar systems, finally, about their manner of dating individual events of their lives. .,