The position of one star relative to another seems fixed to us. However, the stars are moving, usually at great speed.
Because of the huge distance between the stars and us, this movement can only be realized with the use of appropriate instruments or over the centuries.
Because it seems that the stars are fixed in the sky, we can imagine grouping them into constellations. In these clusters, the stars seem to us who observe them from Earth to be close to each other. In fact, they may be very far apart, sometimes separated by tens of light years.
In the Southern Cross constellation, for example, to the Earth-based observer, the stars appear to form a cross. But if an observer, located elsewhere in space, saw this constellation, he would probably be unable to perceive the figure of the cross.
During the year, we noticed the Southern Cross in different positions with respect to the terrestrial observer; However, it always maintains the same position in relation to the other constellations. In fact, it is the Earth - our vantage point - that is moving.
People of various civilizations observed that at a time when their arid lands were attacked by scorpion plagues, a certain set of stars appeared in the sky. In their imagination it was a great celestial scorpion. Based on the emergence of the constellation Scorpio, the Mesopotamian peoples predicted the dry season.
The constellations served as a reference to delimit the seasons of the year, distinguish the seasons of drought and planting, build calendars and identify guide stars for navigations.
Brazilian indigenous peoples, like other peoples, imagined figures in the sky as they looked at the stars. Each culture has its own constellations.
Officially in 1888 astronomers grouped the stars and divided the sky into 88 constellations officials with precise borders. Thus each direction in the sky necessarily belongs to one (and only one) of them. They were mostly baptized according to tradition from ancient Greece, and their official names are always in Latin. The best known, for example, are the ones that make up the Zodiac: Aries (ram), Taurus (the bull), etc.