Do you know the origin of constellations?

We are familiar with the twelve constellations such as Aries, Taurus, Gemini and Cancer. Do you know who invented it? And what is the origin of the word constellation? Have you ever understood it? Then, this issue of constellation knowledge will give you a long knowledge! Let's take a look at Bian Xiao!

Constellation is an indispensable part of astrology and a group of stars in the sky. Since ancient times, human beings have associated three or five stars with their mythical figures or artifacts, which are called "constellations". Constellation is a means to determine the orientation of the sky in almost all civilizations and is widely used in the field of navigation. The division of constellations is completely artificial, and different civilizations have different divisions and names. Constellations have no uniform and precise boundaries. Until 1930, in order to unify the complicated constellation division, the International Astronomical Union divided the sky into 88 official constellations with precise boundaries, so that every star in the sky belonged to a specific constellation. Most of these official constellations are based on ancient Greek myths handed down from the Middle Ages. In contrast, some widely circulated star combinations are not recognized as official constellations, such as the Big Dipper (see star list).

In the three-dimensional universe, there is no necessary connection between these stars. Their positions on the celestial sphere are similar, but in fact they may be far apart. If we were in another solar system of the Milky Way, the starry sky we saw would be completely different. Since ancient times, people have been interested in the arrangement and shape of stars, and naturally linked some stars with similar positions to form constellations.

Mesopotamian astrologers divided the starry sky into several regions for the convenience of studying and observing many stars in the sky, and each region was a constellation. It's hard to say clearly when humans began to have the concept of constellation. This astronomical knowledge was known long before there was a historical record. [2] The name of the constellation probably comes from the sailors who sailed early.

The origin of constellations may be completely different between civilizations in different regions, but with the expansion and mutual influence of civilizations, the culture of constellations also includes the process of integration.

Constellations have long been regarded as an important symbol for sailors and travelers to distinguish their directions. With the development of science and technology, the role of constellations in direction identification has gradually weakened, but spacecraft still determine their position and course by identifying bright stars. For starry sky lovers, the identification of constellations is often the identification of bright stars.

In the northern hemisphere, the Polaris in Ursa minor is the most important basis for determining the direction in the starry sky. It can be seen from celestial coordinate system that the height of Polaris is consistent with the local latitude; But in fact, because the North Star is not bright, people usually use the Big Dipper to find the North Star, so as to determine the direction. You can find Polaris by extending the handle of Beidou five times. In the case of low accuracy requirements, it can be considered that the direction of Polaris is the north. In the low latitudes of the northern hemisphere, the Big Dipper will fall below the horizon. At this time, according to the "M" (or "W") Cassiopeia opposite the Big Dipper, the position of the North Star can be determined.

Once Polaris and any other star are identified, the whole starry sky can be identified completely by the relative positions of the stars. In order to facilitate memory, people usually look for arcturus, the patriarch, and arcturus, the Virgo, through the bucket handle extended by the Big Dipper. In different seasons, you can also locate Gemini, Canis major, Canis minor, Taurus, Auriga and even Leo through the bright Orion in winter. In autumn, you can find Andromeda, Perseus, Pisces and so on through the autumn quadrangle of Pegasus. The summer triangle is the most easily found feature in the summer sky. At this time, you can find Cygnus, Lyra, Eagle, Sagittarius, Scorpio and Draco.

The constellations near the South Celestial Pole are scattered, with many smaller constellations and few bright stars, and there are even no bright stars in many areas, which is relatively difficult to identify. In addition, there is no indicator star such as Polaris in the southern celestial pole, so the southern celestial pole is often determined by the extension of the cross I (Southern Cross) and the cross II (Southern Cross) of the Southern Cross by about 4.5 times. At the same time, Centauri, Centauri, Carina and Pojiang in the South Gate are all important bases for identifying the southern hemisphere constellations. [ 1]

In 270 BC, the Greek poet Aratus wrote Things, in which 47 constellations were mentioned. According to the star regions recorded in Celestial Bodies, due to precession, the Antarctic in the period described in the book is not consistent with the current Antarctic, so it can be inferred that the starry sky recorded in the book is before 2000 BC; At the same time, the blank area of the starry sky record indicates that the observer should be near 35 to 36 north latitude. So some people think that the practice of dividing the starry sky into constellations originated from Babylon and Sumer in Mesopotamia, and the constellations of Greece and Egypt may have been introduced from this area.

In the Book of Job, several constellations such as Bear and Orion are mentioned. In the12nd century BC, the land landmarks built in the era of Nebuchadnezzar I were engraved with designs of Sagittarius, Scorpio and Ophiuchus. The ancient Greek poets Homer and hesiod also mentioned Ursa major, Orion and the Pleiades (the Pleiades was considered as an independent constellation at that time, not a part of Taurus), and at the same time, Babylon had recorded the zodiac in cuneiform.

In the second century, Ptolemy recorded 1022 stars in 48 constellations in his astronomical masterpiece, which is also the embryonic form of modern constellations. After that, many astronomers filled the Ptolemaic constellation with new constellations. Valle in 1603, Jahannes Hewelius in 1690, and Llakaj in 1752 have named the constellations in Nantian in two centuries. [3]

It seems that the movement of the constellation with the celestial sphere is caused by the movement of the earth itself, in which the rotation and revolution of the earth are the most obvious changes in the starry sky. Due to the rotation of the earth, the starry sky background rotates once a day around the celestial axis; The starry sky also changes slowly with the seasons. A year has passed, and the starry sky is almost the same as it was a year ago. The rotation axis of the earth's rotation also has a long-term motion, called precession, with a period of about 25,765 years. This movement causes the periodic drift of the North Pole in the background of stars, which is called precession in astronomy. A cursory observation of the constellation in a short time can ignore this movement.

The stars are moving at high speed. The motion of stars can be decomposed into the radial velocity of their connection direction and the self-nature perpendicular to it, in which the self-nature will change the apparent position of stars in the starry sky. Because the star is too far away from the earth, it can generally be considered that the position of the star in the sky is fixed.

Because the apparent positions of the sun and planets relative to the earth are not fixed with the positions of the background stars on the celestial sphere, they periodically pass through the 13 constellation on the ecliptic. In astrology, it is often described as "Mercury is in Scorpio". However, there are only twelve constellations in astrology, and they are equally divided.