Rus Articles Journal

How in the ancient time determined duration of lunar month?

Already primitive person paid attention that the Moon periodically changes the appearance. At first in the evening sky the thin light strip in the form of a narrow sickle appears. Gradually the strip extends and within several days increases to a semicircle...

In several days in a night firmament the full disk of the Moon which later a certain number of days turns into a semicircle again shines, and then - in a narrow sickle. And then the Moon absolutely disappears from the night sky.

Such transitions were called Moon phases subsequently: new moon, first quarter, full moon, last quarter. The period between two identical phases received the name lunar (sinodichesky) month which originally was defined in 30 days. It was established later that in lunar month about 29 and a half days.

Never it seemed to you strange that at our night star two names? And this phenomenon is peculiar not only to Russian (The moon - month), but also to many other languages. For example, in Greek ( mene - Moon, Man - month), in English ( moon - Moon, month - month).

Because the movement of the Moon around Earth is carried out on an elliptic orbit, and also becomes complicated also by Sun attraction force, the actual duration of lunar month is ranging from 29 days 6 hours 15 minutes till 29 days 19 hours 12 minutes. Therefore now the average duration of lunar (sinodichesky) month, to equal 29 days 12 hours 44 minutes 2,8 seconds of average solar time, or 29,53059 averages of solar days is applied.

Lunar month was of great importance in calendars of many ancient people: and some others.

Should mark out Babylonians, Chinese, Indians, Jews that dates of the Jewish holidays are celebrated according to a lunar calendar. It was for this purpose necessary to consider duration of lunar months, and precisely the nobility what day in a lunar calendar today. From the point of view of the Jewish law of Galakhi, it was very important correct to define day of a new moon ( it is young - birth), when is born new moonlight.

At the beginning of our era ancient Jews possessed way of determination of exact value of size of lunar month.

For the first time calculation of lunar month occurs in the Jewish Talmud in the treatise devoted to the Jewish new year (the treatise Rosh of hectare - Shana, W, the sheet 25a). Rabanne Gamliel declared to the tribespeople:

There is no new moon before twenty nine and a half days (twelve hours) of both two thirds of hour, and seventy three parts .

I want to remind readers that the Jewish hour was divided into 1080 parts ( halaky ), and each part ( helek ) - for 76 moments ( regay rega - moment).

And now let`s count Rabanne Gamliel`s words provided in the Talmud.

We already have 29 days and 12 hours, that is 29,5 days.

Two thirds of hour make 720 parts ( halaky ) . We divide 1080 on 3 and we multiply on 2.

Is added to this number 73 more parts. 793 parts turn out: 720 + 73.

Is defined what part of hour is made by this number. Let`s divide 793 for 1080 (quantity of parts of hour) and we receive 0,734259 hours. we will define

Now what part of day is made by this time. For this purpose we will divide 0,734259 on 24 (a number of hours in days). We receive 0,03059 days.

we Will add this number to 29,5. We receive the following number: 29,53059 days.

As you can see, this number from the Talmud completely coincides with the number given in the beginning of article. It is asked: how people could calculate at that time yes sir value of lunar month?

To be fair, it is worth giving two more interesting examples.

Ptolemaeus in Almageste gives just the same value for duration of sinodichesky month. And Ptolemaeus as modern scientists consider, got data from not remained star catalog of Gipparkh.

The cuneiform table ACT 122 found in Babylon consists of several columns which give the movement of the Sun and Moon, time and sizes of eclipses. The seventh column contains duration of lunar months, and their average makes 29; 31,50,8,20 days that just corresponds to duration of sinodichesky month of the Judaic calendar which is written down in 60 - river system of calculation. On the lower edge of the table the name the Babylon astronomer Kiddina is written down.

Here such story about calculation of duration of lunar month.