From Aries to Pisces
The primacy in the "calendar" field undoubtedly belongs to the Egyptians. If some scholars are to be believed - already in 4241 year BCE. priests of On, one of the oldest capitals of Egypt (later named Heliopolis by the Greeks), they arranged the first solar calendar, based on observations of the Sirius-Sopdet movement. Also the Sumerians, who developed a high culture in Mesopotamia even before the Babylonians, they began their astronomical observations very early (their heirs were the Babylonians). The oldest sources prove, that they practiced astronomy as early as the 2nd millennium BC. The origins of Sumerian-Babylonian astronomy, however, are undoubtedly older. In the third millennium BC. The Sumerians were already able to calculate the Moon's orbital time around the Earth with accuracy, which was achieved by Europeans only in… 1897 year. Old chronicles provide, that the Chinese also achieved a high level of knowledge of astronomical phenomena. In the book "Szu-Cing", attributed to Confucius (6th century. p.n.e.), tells the story of the astronomers Hi and Ho, who, indulging in bad games (m. in. drinking wine), they had neglected their duties of watching over the heavens and had not foreseen a solar eclipse. The effect of this was terrible: the unannounced eclipse caused panic in many provinces of the country, making, that the authority of the Son of Heaven, that is, the emperor, has suffered a lot. Emperor Chiang-Kang (ok. 2150 r. p.n.e.) so he condemned astronomers to death. But regular astronomical observations existed in China before. As it follows, knowledge about the movement of the sun and moon was already in the 5th-3rd millennium BC. quite a lot.
And knowledge about stars and planets?
Old Babylonian legend says, that before the god Marduk began to create the world - he cared first of all for the gods. He built a house for each of them, and from then on, no worthy divine person wandered on the Earth and in the sky, and she had a permanent address. They were constellations. Then the god Marduk instituted a period called a year and divided it into 12 months. Each month got po 29 days, and on top of that - three constellations. Then he formed the constellation Nibiru (Great Bear), to show the other constellations in the sky. The cleaning up of the starry sky was therefore very early and it is certain, that after the Sun and the Moon, individual groups of stars and some brighter planets were distinguished. It was noticed quite early, that the stars, which - like the Sun and the Moon - were created for human comfort, they are not only ornaments "glued" to the dome of heaven, but they run their course, though slower than the sun and the moon.
Noticed, that over 12 months of the year can be specified 12 groups of stars lying on the road, which the Sun runs along the sky, that is, the ecliptic. Looking for the similarities of geometric figures (into which individual groups of stars could be combined) to human and animal imaginations, they were given names taken from religious beliefs.
It is believed, that the first constellation, who was given a name, there was a Taurus - a symbol of spring plowing, and also fertility. It is distinguished in the sky by a bright star (Aldebaran), it is therefore useful for measuring time. It has gone over 2 200 lat p.n.e., when the sun was near the Hyades at the vernal equinox (star cluster, which includes Aldebaran). Other constellations located in the ecliptic were given their names a little later. We guess, where did their names come from: Gemini is named after the two bright stars of Polydeukes (Castor and Pollux), the sons of Zeus and Leda, being symbols of brotherly love, Libra - from the fall equinox, Sagittarius - from the hunting season, and Capricorn, Aquarius and Pisces - from the wet winter period, which they represent.