The Nile was vital to Egyptian culture since the stone age. Climate change and desertification Sahara around 8000 BC. C. forced the migrated and settlement in the Nile river valley, where they develops an agricultural economy and a centralized society. With the division of labor arises the system numerical and the division of the day in 24 hours. At the beginning of the third millennium B.C. the Egyptians had a base 10 numbering system. The Egyptian calendar, unlike the Babylonian, which was with the Moon, was based on the solar cycle. In the millennium IV a. C. the solar year of 365 days was known, with 12 months of 30 days and 5 complementary days. The The beginning of the year was determined by the heliacal rising of the star Sirius, that is, by its first appearance at dawn after a period of invisibility. This event originally coincided with the Start of the natural rising of the Nile.
Later observations revealed a delay in the heliacal rise of Sirius, and the rising of the Nile did not coincide again until 1460 years later (Sothian period). Hence it followed that the true length of the year was 365.25 days. From 238 a. C. was therefore added to every fourth year an interspersed day. Apart from various stellar constellations, there existed in Egypt a division of the zodiac into 36 deans, ruled by divinities.
Chinese philosophers made important advances in the fields of science, technology, mathematics, astronomy and symbol-based writing. From this nation, come the first records with observations not only of comets and solar eclipses, but also of supernovae. The story of the unfortunate court astronomers Hsi and Ho, who were executed for endangering the safety of the world, by failing to predict an eclipse of the Sun. As in Babylon, the ancient Chinese calendar from the early 2nd century BC. C. is a lunisolar year with 19-year leap cycles. The work Calendar of three cycles, appeared towards the beginning of our era and whose author is Liu Hsin, describes the history of Chinese astronomy since the third millennium. The astronomers of the Chinese imperial court observed extraordinary celestial phenomena whose description has come in many cases to this day. These chronicles are a very valuable source for the researcher because they allow check the appearance of new stars, comets, etc. Eclipses were also recorded in this way. On the contrary, the study of the planets and the Moon did not exist until the 1st century BC. C. in conditions of provide sufficiently accurate predictions of celestial phenomena and eclipses. The old one Chinese solar astronomy differs greatly from Babylonian and Western. The celestial equator was divided into 28 houses and the number of constellations amounted to 284, which shows the detail in the observation of the sky.
CENTRAL AMERICA AND PERU
If the different peoples of ancient Mexico reached the hieroglyphic phase, the Mayans achieved the syllabic-alphabetic phase in their writing. The numbering initiated by the Olmecs with a vigesimal base, is perfected by the Mayans, in the 3rd and 4th centuries BC. C … The Mayans knew from the third millennium BC. C. at least one very multifaceted astronomical development. Many of his observations have survived to this day (for For example, a lunar eclipse on February 15, 3379 BC. C.) and the revolutions were known with great accuracy synodics of the planets, the periodicity of eclipses etc. The calendar starts on a zero date that possibly it is June 8, 8498 BC. C. in our reckoning of time, although it is not entirely certain. The Mayans also had a year of 365 days (with 18 months of 20 days and an interspersed month of 5 days). Also Inca astronomy, in Peru, had in part a great development. The Incas, they knew the revolution synodic of the planets with admirable accuracy. The annotations on the quipus (knotted cords) give 115.88 days for Mercury, 584.8 days for Venus and 398.88 days for Jupiter. Modern values are respectively 115.88 d, 583.92 d and 398.88 d. The calendar consisted of a 365-day solar year, spread over in 12 months of 30 days and 5 interleaved days. All cultures belonging to the period of development discussed had one thing in common, and that is that they took celestial phenomena as given phenomena, without looking for hidden explanations at all. To Earth was attributed the shape of a flat disk, surrounded by the celestial vault.