The Rasi chart that is prepared of the placement of the planets at any given time of the day represents the planetary positions at that moment. The casting of the chart indicates the position of the planets in the 12 rasis.
The planetary positions chart has 12 squares, each of which represents one of the 12 rasis of the zodiac. Beginning Mesha, which is represented at the second square from top left, the rasis are counted in clockwise direction. Each square represents one Rasi, the final Rasi in the planetary positions chart being Meena rasi.
At any point of the day, each of the planets are positioned in one of the rasis. The rasi chart is thus drawn with the planets positioned in the appropriate rasi for whatever time the planetary positions are to be known.
Planetary positions at the time of birth
The position of Moon in the zodiac, will determine the rasi of the baby. At the time of birth, if the Moon is in Dhanu Rasi, then the baby is deemed to be of Dhanu Rasi.
Lagna at the time of birth
The ascendant sign at the time of birth is called the Lagna. If the Mesh rasi is the rasi that is rising at the time of the birth then the baby's lagna is said to be Meena lagna.
Planetary positions and the 12 houses
Each of the rasi's houses, counting to 12, represent one aspect of the individual's life. For example, the first house represents the basic self and dignity, with the following aspects of the individual such as ambitions, character, fame, health, longevity, vigour, dignity, head, heart and personality. Similarly, the others.
Thus, the planetary positions indicate the quality and quantity of a specific time in period, representative of the period of the day for an individual, with reference to his/her birth chart.