Constellation and Gregorian calendar

The origin of the constellation:

After the culture of the two river basins spread to ancient Greece, it promoted the development of ancient Greek culture. Astronomers in ancient Greece supplemented and developed the Babylonian constellation and compiled the ancient Greek constellation table. In the 2nd century A.D., Ptolemy, an ancient Greek astronomer, synthesized the astronomical achievements at that time and sorted out 48 constellations.

After the Middle Ages, European capitalism rose and needed to expand outward, and the navigation industry was greatly developed. When a ship sails at sea, it needs navigation at any time, that is, to determine the position and course of the ship at sea. Sailing in the vast sea, stars are the best lighthouses and navigation marks, so Europeans attach great importance to their observation. To observe stars, we must first choose the observation objects. Because the stars in the constellation are bright and the shape of the constellation is special, it is the easiest to choose the observation object in the constellation, so the constellation has received extensive attention.

/kloc-in the 6th century, when Magellan sailed around the world, he not only used constellations to navigate and orient, but also studied constellations. Before Magellan sailed around the world, people only knew that there were constellations in the sky in the northern hemisphere, but Magellan extended the horizons of astronomers to the southern hemisphere, and he found many constellations in the sky in the southern hemisphere. Thanks to the work of Magellan and others, by the beginning of the 20th century, all-sky constellations had been basically delineated, and it was time to unify the constellations. 1922, the General Assembly of the International Astronomical Union decided to divide the sky into 88 constellations, and the names of the constellations basically followed the historical names. 1928, the international astronomical union officially announced the names of 88 constellations. These 88 constellations are divided into three celestial regions, 29 in the northern hemisphere and 47 in the southern hemisphere, near the ecliptic 12.

It should be pointed out that the modern constellation is no longer a pattern of several bright stars, but represents a certain area of the sky, including both bright stars and dark stars invisible to the naked eye. Constellations are also different in size. The two largest constellations are Ophiuchus and Virgo, and their areas are 1300 square degree and 1290 square degree respectively (square degree is the unit of area on the celestial sphere, and 1 square degree is equal to 1/4 1253 of the whole sky area). The smallest two constellations are Sagittarius and Southern Cross, with an area of only 72 square degrees and 68 square degrees. The constellation size is 20 times different!

In the long-term observation and practice, people gradually understand that the starry sky is not mysterious, and the stars that people can see with their eyes can be counted. The ancients counted by hand, and later counted by scientific methods. Hey, they really did the math! Stars with brightness above 6 can only be seen with eyes. There are only 6000 such stars in the sky. The ancients also found that the stars in the sky seem to be chaotic, but in fact their distribution is regular. People created constellations according to the distribution law of stars. Archaeological excavations have proved that human beings have known constellations for more than 7000 years.

An ancient tomb with a history of 7,000 years was excavated in Puyang, China. People found patterns of "dragon" and "tiger" made of clam shells and "Beidou" made of bones in the tombs. Experts initially believe that these "dragons", "tigers" and "Beidou" are constellations. Patterns similar to constellations were also found in the pyramids of ancient Egypt, indicating that ancient Egyptians knew about constellations 5000 years ago.

However, the well-documented constellations originated in Babylon, and the Babylonians put forward 30 constellations around 1000 BC. Babylon is located in today's Middle East. The Tigris River and the Euphrates River flow into the Persian Gulf from northwest to southeast, so it is also called the "two-river basin" area. The two river basins are rich in land and pasture, suitable for human survival, and the city of Babylon was established very early. In BC 1894, nomadic people from the Syrian grassland established the "Kingdom of Babylon" in the city of Babylon. This is one of the four ancient civilizations in the world. Located in the middle reaches of the Euphrates River, the city of Babylon is on the main road of trade and transportation, so the kingdom of Babylon flourished rapidly and created a relatively developed ancient culture. In the official documents of the ancient Babylonian kingdom, there are many records about astronomical phenomena, including planets, stars, meteors, comets, eclipses and constellations.