The Zodiac (from the Greek word Zoodiacos Cyclos which means the Animal Circle) is an imaginary belt in the sky with a width of 18 ° centered on the ecliptic circle, but this term can also refer to the constellations of stars passed by the belt, which now number 13. It is believed that the origin of this concept came from the Eufrat River Valley civilization possibly with only 6 constellations: Capricornus, Pisces, Taurus, Cancer, Virgo, and Scorpio, which were then split into 12 due to the 12th full-moon sighting of the full moon on successive parts of the belt.