Why is there a constellation of 12?

The well-documented origin of the twelve constellations originated from Babylon, and the Babylonians had already proposed 30 constellations around 1000 BC. After the culture of the two river basins (Babylon) spread to Greece, ancient Greek astronomers supplemented and developed the Babylonian constellation and compiled the ancient Greek constellation table. 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. Ships sailing at sea need navigation at any time, and stars are the best street lamps. Among the stars, this constellation has a special shape and is the easiest to observe. Therefore, constellations have aroused widespread concern. 16 when Magellan actually sailed around the world, he not only used constellations to navigate and orient, but also studied constellations. 1922, the General Assembly of the International Astronomical Union decided to divide the sky into 88 constellations, and their names 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. And the constellation we usually say is the 12 constellation on the ecliptic. Each of them has some myths and legends about himself. In ancient times, in order to facilitate navigation and observe astronomical phenomena, people connected the scattered stars in the sky through imagination. Half of them were named in ancient times, and the naming method was based on the myths and forms of ancient civilizations (including the myths and epics of Mesopotamia, Babylon, Egypt and Greece). The other half (mostly in the night sky in the southern hemisphere) was named only in modern times, and is often named after navigation instruments. In ancient times, because of different regions, the way to see the starry sky was different! Now the world divides the sky into 88 regions and 88 constellations according to the constellation map. The "constellation" we usually say refers to the "sun constellation"; That is, people on the earth are the center, and at the same time we can see which constellation the sun is in orbit (Greek zodiac: the circle made by animals, also known as the "zodiac"), so we can say what constellation that person is. More than 2000 years ago, the Greek astronomer Hipparchus (190 ~ 120 BC) divided the ecliptic into twelve segments, with spring divided into zero, and every 30 degrees from the vernal equinox (that is, the zero degree of the ecliptic) as a palace, taking the main constellations contained in each palace at that time. Babies born when the earth moves to every bisector (constellation) will always have some similar characteristics when they grow up, including behavioral characteristics and personality characteristics. Connect these associations (rich imagination and creativity) in series to make the humanity of these constellations concrete; It also adds the color of myth and becomes an important part of culture (mainly Greek and Roman mythology). This set of numerology has been developed and circulated for at least five thousand years, represented by these twelve constellations respectively. But these constellations do not represent a certain "star", but can only be regarded as "representative symbols of the same name". Astronomical knowledge of the twelve constellations Astronomical names of each constellation (zodiac sign) [arranged in alphabetical order of Latin names] Palace number Latin name English name Chinese name 1 1 Aquarius 1 Aries Aries 4 Cancer Cancer Cancer 10 Capricorn Aries Capricorn. Gemini Gemini Leo Lion Lion 7 Libra Libra 12 Pisces Pisces 9 Sagittarius Sagittarius 8 Scorpio Scorpio. 2 Taurus Taurus 6 Virgo virgo virgo female Aries every year 65438+8 o'clock in mid-February, Aries is above our heads. This is a very dark small constellation, in which only the next 2.3m α star and 2.7m β star are slightly meaningful. The four stars Pegasus and Andromeda in the autumn sky make up a big box. Draw a straight line from the two stars in the north of the box and extend it to the east for one and a half times, and you can see Aries. In winter in Taurus, there is a very bright 0.86-meter star (13 of all-day stars) in the sky not far northwest of Orion. It is the alpha star of Taurus, which was called Bisuwu in ancient China. Taurus is also one of the famous zodiac signs, and Bi Suwu is located near the zodiac signs. It is about 90 degrees away from four bright stars, such as Xuanyuan XIV of Leo, Antares of Scorpio and Beiluoshimen of Nanyu, and is also near the zodiac. They are called the "four heavenly kings" of the zodiac. The most famous celestial body in Taurus is "two clusters plus a nebula". Connecting Orion γ star and Cebu star, extending about twice the distance to the northwest, there is a famous open cluster-Pleiades cluster. People with good eyesight can see seven bright stars in this cluster, so it was also called "Seven Star Cluster" in ancient China. The Pleiades cluster is 4 17 light-years away and has a diameter of 13 light-years. Observed with a large telescope, it can be found that there are more than 280 stars in the Pleiades cluster. Another open cluster is called Biju Cluster, which is located near Biju, but Biju is not a member of it. Bi cluster is 0/43 light-years away from us/kloc-and is the closest cluster to us. You can see five or six stars with the naked eye. In fact, it has about 300 members. Near the star zeta in Taurus, there is a famous big nebula, which was named "Crab Nebula" by a British astronomer according to its shape. Astronomers in this century infer that the Crab Nebula is the product of 1054 supernova explosion. The supernova explosion of 1054 is recorded in detail in ancient astronomical documents in China. Gemini extends the connecting line between beta star and alpha star of Orion to the northeast, and can meet two bright stars which are not far apart. The brighter one is beta star of Gemini, with brightness of 1. 14, etc. The dimmer star is Alpha Gemini with a brightness of 1.97. A series of stars τ, ε, μ starting from α star is almost parallel to another series of stars τ, ζ, γ starting from β star. They are imagined as two friendly brothers-casto and Poole Jocks. Brother-β star, known as "North River III" in ancient China, is brighter than brother-α star and is the 17th brightest star in the whole day. Brother Alpha, known as "Beihe II" in ancient China, is the first confirmed binary star in the history of astronomy. In fact, it is a "six-star" composed of six stars. Interestingly, my brother Beichuan is also a Liuhe star. These two brothers are really twins. How much they look alike! Cancer in spring, cancer is in the west of Leo and the snake head is in the north. This is the darkest of the zodiac signs. The brightest star in the constellation is only 3.8m, so you can't see the shape of a crab at all. This may be because Hercules had already beaten it to pieces. That's right, it still clings to the long snake and goes along with it! Near the Delta Star in the center of Cancer (or between the two bright stars of Leo Xuanyuan XIV and Gemini Beta), people with good eyesight can see a small white fog, which is described in China's ancient book: "Like clouds and Feiyun, like stars instead of stars, just seeing gas." It was not until the invention of the telescope that people observed that it was originally a cluster, which was called "hive cluster" in astronomy. This cluster has more than 200 members and is 520 light years away. Astronomically speaking, star clusters can be divided into two categories, one is the "globular cluster" in Ursa Major, and the other is the "open cluster". These clusters are irregular in shape and generally distributed on silver disks. Astronomers have discovered more than 1000 open clusters in the Milky Way. They estimate that the number of open clusters in the whole galaxy must exceed 10000. Leo once mentioned Leo when he introduced Capricorn and Virgo in Night Sky in Spring. The constellations of beta star in Leo, arcturus in Capricorn and Virgo form an important "Spring Triangle" in spring night. Leo is also the zodiac sign. Due to precession, the apparent motion of the sun just passed Leo in June every year more than 4,000 years ago. It's June, and the obvious movement of the sun has reached between Taurus and Gemini. At that time, people in the ancient Persian Gulf country of Chaldea thought that the sun got a lot of heat from Leo, so the weather became hot. The ancient Egyptians felt the same way, because at this time of year, many lions moved to the Nile Valley for the summer. Ancient Egypt worshipped Leo very much. It is said that the famous Sphinx is shaped by the body of a lion and the head of a maid. The star of Leo was also highly valued in ancient China, and was called the God of the Yellow Emperor and Xuanyuan. After we found the beta star of Leo through the spring triangle on a spring night, a big star to its east was all Leo's. In Leo, delta, theta and beta stars form a remarkable triangle, which is the lion's back and tail. These six stars from ε to α form the shape of a sickle, which is also like a reverse question mark. This is the lion's head. When the Polaris connecting the constellation Ursa major (that is, the two stars in the spoon mouth) extends in the opposite direction to Polaris, you can find it. Alpha star is called Xuanyuan XIV in China, and its apparent magnitude is1.35m. It is the brightest star in Leo, and it is the 2nd1in the whole day. It forms an isosceles triangle with arcturus and arcturus, and can be found by extending the δ and γ stars of Ursa Major ten times. In ancient times, navigators often used it to determine the position of ships in the sea, so Alpha Leo was awarded the title of "one of the nine navigation planets". Leo's Xuanyuan XIV is located near the ecliptic, which is about 90 degrees away from the four bright stars Taurus, Scorpio Antares and Nanyu's Beiluoshimen. They are called the "four heavenly kings" of the zodiac. Every year in June165438+1mid-October, especially in the nights of June 14 and June 15, a large number of meteors will appear near ζ star with question marks written on Leo. This is the famous Leonid meteor shower. It peaks every 33 years. As early as 93 1 year, it was recorded in China in the Five Dynasties. At the peak of 1833, meteors exploded near zeta star like fireworks, with tens of thousands of them every hour. Therefore, the next night, a farmer hurried outside to see if all the stars in the sky had fallen out. Once I mentioned Leo when I introduced Capricorn and Virgo in the spring night sky. The constellations of beta star in Leo, arcturus in Capricorn and Virgo form an important "Spring Triangle" in spring night. Leo is also the zodiac sign. Due to precession, the apparent motion of the sun just passed Leo in June every year more than 4,000 years ago. It's June, and the obvious movement of the sun has reached between Taurus and Gemini. At that time, people in the ancient Persian Gulf country of Chaldea thought that the sun got a lot of heat from Leo, so the weather became hot. The ancient Egyptians felt the same way, because at this time of year, many lions moved to the Nile Valley for the summer. Ancient Egypt worshipped Leo very much. It is said that the famous Sphinx is shaped by the body of a lion and the head of a maid. The star of Leo was also highly valued in ancient China, and was called the God of the Yellow Emperor and Xuanyuan. We crossed the Spring Triangle on a spring night and found the lion.

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