The celestial sphere is divided into 12 equal parts of 30 degrees each. Each of which represents a zodiac sign. There are 12 different signs. Wherever you are born on earth, there is a local horizon, the line where earth and the sky meet. The whole zodiac belt seems to ascend from eastern horizon and descend to the western horizon due to the daily rotation of earth around its own axis. At a particular place and time of birth, the exact point or the degree of the sign that is rising on the eastern side of the horizon is considered to be the starting point of the houses division, it is also the Ascendant. This is because Sun rises from the east and the rising of Sun means new beginning.