• What is a constellation?
• How many constellations are there?
• What are the main constellations?
• zodiac constellations
• family constellations

We explain what a constellation is in astronomy and which are the main ones. Also, what are family constellations.

The ancient peoples gave the constellations their pseudo-religious explanations.

What is a constellation?

In astronomy, a constellation is a grouping of different stars in a portion of the celestial vault, which apparently evokes a certain shape or silhouette, from which a name is given. These are completely arbitrary associations, which often respond to figures and symbols from the culture, and therefore vary from one society to another

The first constellations were identified in ancient times, when the cousin cultures of the Euphrates Valley dedicated themselves to observing the sky more carefully, and recognized the recurring presence of the same stars in the same regions of the sky.

The different ancient peoples they gave this fact their own pseudo-religious explanations, commonly linked to their founding stories. So, for example, the ancient greeks they saw in them their heroes and their gods, while the ancient Chinese distinguished a set of celestial houses and mansions, and the Incas a set of sacred animals.

In the case of Western astronomy, the constellations established by the Greco-Roman predecessors, mainly those from Greek mythology, are considered in existence.

In fact, the word constellation It is a legacy of Latin constellatus, made up of the voices com- (“together” or “union”) and Stella ("star"); and this language is also used to name the constellations and the stars that constitute them, for which the Latin declensions of the nominative and the possessive genitive are used. Thus, the centaur constellation is called centaurus, but the main star of the set is called alpha centauri, that is to say, “the first of the centaur”.

How many constellations are there?

According to the International Astronomical Union, 88 constellations are formally recognized. Of these, 47 were identified and named by the Greek astronomer and mathematician Claudius Ptolemy (c.100 – c.170 AD), who made in 150 AD. C. a celestial catalog with more than 1000 stars grouped in their respective constellations; and 41 were added later, throughout the 16th and 18th centuries, largely thanks to the guidance they offered to navigators and explorers.

The number of total constellations is fixed, but the observable constellations vary depending on the hemisphere of the planet from which it is observed. Thus, the northern hemisphere contains 36 constellations and the southern hemisphere contains 52.

What are the main constellations?

The observable constellations vary depending on the hemisphere from which it is observed.

Some of the best-known constellations in the sky are the following:

Constellations of the northern hemisphere:

• Andromeda constellation. It represents the princess of the same name, daughter of Cepheus and Cassiopeia, who according to the Greek mythology she was chained to a rock to be eaten by Ceto, a sea monster, but later rescued by Perseus. This constellation, one of the largest known, has 152 stars, of which the brightest is Alpheratz (alpha andromedae).
• Orion constellation. It represents the greatest hunter of Ancient Greece, visible as a warrior holding his weapon and his shield. This hunter was the protagonist of numerous myths Greeks, in some of which he was the pursuer of the Pleiades, the daughters of the Titan Atlas. This constellation is visible from both the northern and southern hemispheres, and is recognizable by the three nearby stars that make up its belt. In total, Orion consists of 204 stars, of which Rigel (beta orionis) is the main and brightest.
• Cassiopeia constellation. It represents Cassiopeia, wife of the king of Ethiopia according to Greek mythology, whose beauty and vanity caused the wrath of the god Poseidon, who sent a sea monster to scourge the shores of his kingdom. This constellation consists of 157 stars, of which the brightest is Tsih (gamma cassiopeiae).
• Perseus constellation. It represents the classical Greek hero of the same name, responsible for beheading the jellyfish and rescue Andromeda, his future wife, from the jaws of a sea monster. The famous Perseid meteor shower is produced inside it, and it consists of a total of 158 stars, of which Mirfak (alpha persei) is the brightest.
• Triangle constellation. It represents, as its name indicates, a triangle, in which the ancient Greeks saw the letter delta (𝛥). It is a minor constellation, at least in Greek mythology, not to be confused with the constellation Triangulum australe, from the southern hemisphere. In this constellation there are only 25 stars, of which Deltotum (beta triangle) is the main one.

Constellations of the southern hemisphere:

• Crux constellation. It represents, as its name indicates, a cross, but since it belongs to the southern hemisphere, it is popularly known as the “Southern Cross”. It is one of the most useful constellations for navigation, since its main axis always points towards the South Pole. This constellation has 49 stars, of which Ácrux (alpha crucis) is the brightest.
• Canis Major constellation.In Greek mythology, it represents the hunter's dog Orion, which is why it seems in the sky to always be following the path of its owner. This constellation has 147 stars, of which Sirius (alpha canis majoris) is the brightest (in fact, it is the brightest in the sky).
• Hydra constellation. It represents the mythological monster of the hydra, a kind of reptile with multiple heads, to which two new ones were born every time the hero decapitated one with his sword. It is one of the largest modern constellations, straddling the Earth's equator, that is, both north and south. It consists of 238 stars, of which the brightest is Alfard (alpha hydra).
• Constellation of the Southern Crown. It represents the laurel wreath that belonged to the wise Chiron, the centaur who was the teacher of numerous Greek heroes in mythology. It is a small constellation, very close to Sagittarius, consisting of 46 stars, of which Beta coronae australis It is the brightest and largest.

zodiac constellations

A person's sign is defined by the constellation the Sun is in at their birth.

Among all the constellations, there are 12 that occupy a particular place in the celestial vault: an imaginary band 18 degrees wide, centered on the ecliptic (that is, on the apparent path of the sun along the terrestrial sky) and divided into twelve sectors of 30 degrees of longitude of the ecliptic, to each one of which a unique sign corresponds to him.

This band is known as zodiac (from the Greek zodion, "small animal image") since the Greeks identified the constellations located in this strip of the sky with different figures and animals. These twelve constellations are the ones that determine the astral signs of people, depending on which of them (or their surrounding spaces, known as "houses") the person is in. Sun when a person is born.

The constellations of the zodiac are the following:

• Aries (from the Latin Aries). It represents the head and horns of a ram, corresponding in Greek mythology to the ram that saved the lives of the Argonauts Frixio and Hele, who in return sacrificed it to the god Ares, who ascended it to the firmament. Later his skin would be the golden fleece. This constellation is made up of 86 stars, of which Hemal (alpha arietis) is the brightest of all.
• Taurus (from the Latin taurus). It represents the Bull of Crete and at the same time the form that Zeus adopted to kidnap the Phoenician princess Europa and take her to Crete so that she would be her lover. This constellation is made up of 223 stars, of which the brightest is Aldebaran (alpha tauri).
• Gemini (from the Latin gemini). It represents the mythological twins Castor and Pollux, known as the Dioscuri and brothers of the famous Helen of Troy. This constellation consists of 119 stars, and the two brightest are, precisely, Pollux (beta geminorum) and Castor (alpha geminorum).
• Cancer (from the Latin cancer). It represents a crab, an animal present in numerous ancient mythological traditions. It can be found in the Egyptian temple to Hathor, at Dendera; but also in the Greek account of the labors of Hercules, in which the goddess Hera sends a crab to sabotage the hero's efforts to kill the Lernaean hydra. This constellation consists of 104 stars, of which the brightest is Tarf (beta cancri).
• Leo (from the Latin leo). It represents a lion, an animal of symbolic and mythological importance in a large number of ancient peoples, especially the Mesopotamians. In the 1st century AD C. this constellation was reinterpreted to allude to the Lion of Nemea, a creature defeated by Hercules in Greek mythology. This constellation consists of 300 stars, the brightest being Regulus (alpha leonis).
• Virgo (from the Latin Virgo). She represents Astrea, a virginal Titaness from Greek mythology, daughter of Zeus and Themis, representative of earthly justice (and therefore called justice by the Romans) and last immortal to live among human beings. This constellation consists of 169 stars, of which Spike (alpha virginis) is the brightest.
• Libra (from the Latin pound). It represents a balance, an ancient symbol of justice and equity, attributed in Greek mythology to the Titaness Astrea, who embodied earthly justice. This constellation, quite discreet compared to the rest of the zodiac, consists of just 83 stars, of which Zubeneschamali (beta libra) is the brightest.
• Scorpio (from the Latin scorpio). It represents a scorpion, an animal with a wide presence in the imaginary of Mesopotamian, Egyptian and Greek antiquity. In Egyptian culture, it is part of the myth of the hunter Orion, who swore to the gods that he would kill every last animal on planet Earth and was punished by a scorpion, which chased him around the world until it killed him with its sting. This is how the Greeks explained that the scorpio constellation emerges in the celestial vault when Orion hides. The scorpio constellation consists of 167 stars, and among them the brightest is Antares (alpha scorpii).
• Sagittarius (from the Latin sagittarius). It depicts a centaur holding a bow and arrow, and his name means "the archer" in Latin. This centaur corresponds in Greek mythology to Chiron, the wise teacher of many Greek heroes, who was accidentally killed by Hercules with an arrow poisoned with the poison of the hydra. This constellation has 194 stars, of which Kaus Australis (epsilon sagittarius) is the brightest.
• Capricorn (from the Latin capricornus). It represents a male goat or goat, associated in the 1st century AD. c.with the Egipan, a hybrid creature of goat and fish, which the ancient Greeks considered related to the rural god Pan. His rise to the firmament, according to Greek mythology, was due to the discovery of the musical conch, an instrument with which he helped scare away the titans during their war against the Olympian gods. This constellation has only 81 stars, of which Deneb Algedi (delta capricorn) is the brightest.
• Aquarius (from the Latin aquarius). It represents a human figure, sometimes male and sometimes female, holding a jug of water. In some mythological traditions it is the god of the storm, of the rain or the personification of the universal flood, whose role is to purify the Earth; but in Greek mythology he is associated with Ganymede, the cupbearer of the Olympian gods. This constellation consists of 172 stars, of which the brightest is Sadalsuud (beta aquarii).
• Pisces (from the Latin pisces). It represents a pair of fish, creatures universally present in the mythological traditions of the world, but which in the Greco-Roman tradition alludes (according to Eratosthenes in 276 BC) to the great fish that saved Derceto, one of the daughters of Aphrodite, from drown in a lake into which he had fallen. According to other versions, it would be Venus and Cupid, when mother and son fled from the monster Typhoon turned into fish, but tied with a rope so as not to get lost in the immensity of the sea. This constellation has 150 stars, of which Kullat Nunu (nu piscium) is the brightest.

family constellations

Family constellations are known as a pseudotherapeutic method that proposes the existence of recognizable patterns in the families of the people, unconsciously perceived and memorized, to later be reproduced in the intimate relationships of adult life.

This theory, proposed by various German psychiatrists in the 20th century but harshly criticized from a scientific point of view, is distantly related to psychoanalysis, since it proposes the re-enactment of family ties as a way to identify learned harmful affective patterns in the childhood.