Starry sky above your head: 10 facts about the constellations
Constellations are areas of the starry sky. To better navigate in the starry sky, ancient people began to distinguish groups of stars that could be connected into separate figures, similar objects, mythological characters and animals. Such a system allowed people to organize the night sky, making each of its sections easily recognizable. This simplified the study of celestial bodies, helped to measure time, apply astronomical knowledge in agriculture and navigate the stars. The stars that we see in our sky as if in one area, in fact, can be extremely far apart. In one constellation there can be no stars connected at all, either very close or very far from the Earth.
There are 88 official constellations in total. In 1922, 88 constellations were officially recognized by the International Astronomical Union, 48 of which were described by the ancient Greek astronomer Ptolemy in his star catalog "Almagest" around 150 BC. There were gaps in the maps of Ptolemy, especially for the southern sky. Which is quite logical - the constellations described by Ptolemy covered that part of the night sky that is visible from the south of Europe. The remaining gaps began to fill up during the time of great geographical discoveries. In the fourteenth century, Dutch scientists Gerard Mercator, Peter Keyser and Frederic de Hautman added new constellations to the existing list, while Polish astronomer Jan Hevelius and French Nicola Louis de Lacaille completed what Ptolemy had begun. Of the 88 constellations in Russia, about 54 can be observed.
Knowledge of the constellations came to us from ancient cultures. Ptolemy made a map of the starry sky, but people used knowledge of the constellations long before that. At least in the 8th century BC, when Homer mentioned Bootes, Orion, and Ursa Major in his poems Iliad and Odyssey, people already grouped the sky into separate figures. It is believed that the main body of knowledge of the ancient Greeks about the constellations came to them from the Egyptians, who, in turn, inherited them from the inhabitants of Ancient Babylon, the Sumerians or Akkad. About thirty constellations were already distinguished by the inhabitants of the Late Bronze Age, in 1650-1050. BC, judging by the records on clay tablets of Ancient Mesopotamia. References to the constellations can be found in the Hebrew biblical texts. The most remarkable constellation is perhaps the constellation of Orion: in almost every ancient culture, it had its own name and was revered as special. So, in Ancient Egypt he was considered the embodiment of Osiris, and in Ancient Babylon they called "Faithful Shepherd of Heaven." But the most amazing discovery was made in 1972: in Germany, a piece of ivory of a mammoth was found, over 32 thousand years old, on which the constellation Orion was carved.
We see different constellations depending on the time of year. During the year, different parts of the sky (and different celestial bodies, respectively) appear before our eyes, because the Earth makes its annual voyage around the Sun. The constellations that we observe at night are those that are located behind the Earth on our side of the Sun, because during the day, behind the bright rays of the sun, we are unable to discern them.
To better understand how this works, imagine that you are riding a carousel (this is the Earth), from the center of which comes a very bright, blinding light (Sun). You cannot see what is opposite you because of the light, but you can only discern what is outside the carousel. In this case, the picture will constantly change, as you ride in a circle. What kind of constellations you observe in the sky and what time of year they appear, also depends on the geographic latitude of the beholder.
Constellations travel from east to west, like the sun. As soon as it begins to get dark, at dusk, in the eastern part of the sky, the first constellations appear to pass through the entire horizon and disappear with dawn in its western part. Due to the rotation of the Earth around its axis, the impression is made that the constellations, like the Sun, rise and fall. The constellations that we just observed on the western horizon immediately after the sun sets will soon disappear from our field of view so that they are replaced by the constellations that were higher at sunset only a few weeks ago.
The constellations that occur in the east have a daily shift of about 1 degree per day: completing a 360-degree journey around the Sun in 365 days gives about the same speed. Exactly one year later, at the same time, the stars will occupy exactly the same position in the sky.
The movement of stars is an illusion and a matter of perspective. The direction in which the stars move across the night sky is due to the rotation of the Earth around its axis and really depends on the perspective and on which direction the observer is facing.
Looking north, the constellations seem to move counterclockwise around a fixed point in the night sky, the so-called north pole of the world, located near the North Star. This perception is due to the fact that the earth rotates from west to east, i.e., the earth moves to your right under your feet, and stars, like the sun, moon and planets, follow your head in the east-west direction, i.e. on the right left. However, if you turn south, the stars will move like clockwise, from left to right.
Zodiac constellations are those through which the sun moves. The most famous constellations of 88 existing are zodiacal. These include those through which the center of the sun passes over a year. It is generally accepted that there are 12 zodiac constellations in total, although there are actually 13 of them: from November 30 to December 17, the Sun is in the constellation Ophiuchus, but astrologers do not rank it among the zodiac. All zodiac constellations are located along the visible annual path of the Sun among the stars, the ecliptic, at an angle of 23.5 degrees to the equator.
Some constellations have families - these are groups of constellations located in one area of the night sky. As a rule, they assign the names of the most significant constellation. The most "large" is the constellation Hercules, which has as many as 19 constellations. Other large families include Ursa Major (10 constellations), Perseus (9) and Orion (9).
Celebrity Constellations. The largest constellation is Hydra, which extends over 3% of the night sky, while the smallest in area, the Southern Cross, occupies only 0.165% of the firmament. The centaur boasts the largest number of visible stars: 101 stars enter the famous constellation of the southern hemisphere of the sky. The constellation Canis Major includes the brightest star in our sky, Sirius, whose brightness is −1.46m. But the constellation with the name Table Mountain is considered the faintest and does not contain stars brighter than the 5th magnitude. Recall that in the numerical characteristic of the brightness of celestial bodies, the smaller the value, the brighter the object (the brightness of the Sun, for example, is −26.7m).
Asterism is not a constellation. Asterism is a group of stars with an established name, for example, “Big Dipper”, which is included in the constellation Ursa Major, or “Orion’s Belt” - three stars encircling the figure of Orion in the constellation of the same name. In other words, these are fragments of the constellations that secured a separate name. The term itself is not strictly scientific, rather just representing a tribute to tradition.
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