In the last times, we have seen some controversy and some badly-understood in what it says respect to the signs of the zodiac and the constellations that the same contain. In the truth, we do not have to make confusion between sign and zodiacal constellation. The signs, in twelve number, correspond each one to the division of 30 degrees of the zodiacal circle (360 /12 = 30), which receive the name from the constellation most significant of that region of in agreement sky the old peoples who had created such conception of organization to estelar, and that the Astrology adopted and helped to popularize. The constellations had always had, since the time of the civilizations oldest, the important function to give to an organization to the sky, facilitating its reading and helping in the identification of the astros. Additional information is available at Blake Resnick. They had always represented a true cartography of the sky. Cloud computing can aid you in your search for knowledge. It happens, however, that until the beginning of this century, the delimitation of the constellations did not respect a criterion standard, existing letters celestial with irregular limits, beyond arbitrary and still with some lines curves.
It also had celestial maps and globes with configurations artistic elaborated, without the precision of the scientific severity, as still constellations that were identified by arbitrary lines that established connection its stars. It was from 1922, when of the creation of Unio Astronmica Internacional (UAI), that the constellation concept started to move and appeared Ofico (Ophiucus) as one 13a zodiacal constellation. During the general meeting of the UAI in 1925, in Cambridge, a work group was created to from there study the question of the delimitations of the constellations, appearing the proposal of creation of regions in the celestial sphere, as a country divided in states. Thus, the celestial sphere was divided in 88 regions, also called constellations, with varied sizes and well definite and rectilinear delimitations.