☼ Raasi Chakra comprises of 12 houses. Imagine the space round the Earth is divided into 12 equal part. Each part is called a Raasi. While the time derivative of Sooriyan is the Lagna in a horoscope, the house where Chandran falls in the horoscope chart, is called the Raasi. This is also called as Moon Sign.

☼ The horoscope chart which contains the Lagna and the actual positions of the Navagraha is referred as Raasi Chakra. In the northern part of India, this is also called Lagna Chakra, Lagna Kundli and so on, giving emphasis to the fact that the chart is formed and studied on the strength of the Lagna.

☼ Literally, this appears to be more appropriate considering the fact that the study of chart is Lagna oriented. Somehow, in the southern part of the country the term Raasi Chakra has come into usage Both Raasi Chakra and Lagna Chakra refer to the same chart, based on the Lagna of the horoscope.

☼ In a Raasi Chakra, the house in which Chandran (Moon) falls in the birth time, is called its Raasi. Lagna is taken into consideration an the fundamental point in the study of a horoscope and the prospects of the horoscope. Chandran (Raasi) is considered as the basic point in working out the contemporary transitions of Navagraha, like Guru Peyarchi, Sani Peyarchi etc,

☼ The Raasi Chakra comprises 12 Houses (See Chart - Raasi Chakra - below) . When our Nakshatra at the time of our birth, falls into a particular Raasi, then we call it our Raasi. The house where chandran fits in the horoscope indicates this. The place of Chandran in our horoscope is our Raasi. The Lagna is also represented by the Name of the house where it falls.

☼ Within every house in the above chart, the first name is the Name of the Raasi, the second name (within bracket) is the Name of the Lord of that Raasi, the last 3 names are the Nakshatras falling within that Raasi. Numbers 1,2,3,4 respectively mean the Nakshatra Paadams. Nakshatra without number represents the full Nakshatra - that is all the 4 Paadams of the respective Nakshatra. When Lagna falls in any one of the 12 houses, then Lagna is called by the name of the house. For example, if Lagna falls in Meenam, then Lagna is referred as Meena Lagna.

☼ When Chandran falls in any one of the 12 houses, then the Raasi is called after the name of that house. For example, if the Nakshatra is Uthirattathi, Chandran falls in Meenam. Then the Raasi is called Meena Raasi.Our Raasi Chakra (Horoscope Chart) consists of 12 equal parts, which are called Houses or Raasis as it applies. The period of Sooriyan's (Sun) transition through all the 12 houses covers a period of one year. A month according to Tamil calendar corresponds to a Raasi. In calendars of other Indian regions / languages, this may slightly vary this way or that way.

☼ Each house is assigned a name from Mesham to Meenam. Mesham corresponds the first Tamil month Chithirai and each subsequent house, called Raasi, corresponds the subsequent Tamil Month. All the Navagrahas considered in Astrology are not Planets as is generally being believed. Sooriyan (Sun) is not a Planet. It comes under the category of Star. Raahu and Kethu are not Planets - they are physically non-existant forces. In all probablities, Raahu and Kethu are the North and South Poles of the Earth. >Our ancestors derived this art based on astronomical facts. Rishi Pararar is considered the Father of Predictive Vedic Astrology. Astrology is largely a science derived on probablities of the cosmic effect of astronomical transitions.

☼ Each Raasi is assigned its own ruling Graha. A house which is ruled by certain Graha, is called Aakshi house of the Graha ruling the particular house. We have seen that Raahu and Kethu are not Planets. They are described as "Saayaa Grahas" in Astrology. Excepting Raahu and Kethu, all the remaining 7 Grahas (Planets) are assigned their own Aakshi house.

☼ Of the remaining 7 Grahas, Sooriyan and Chandran are assigned as ruling Grahas of one house each. Sooriyan is the Lord of Simham (Leo). Chandran is assigned as ruling Graha for Katagam (Cancer).

☼ The remaining 5 Grahas are assigned two houses each.

☼ There different view points as to the uchcham and Neecham states of Raahu and Kethu. here is an opinion that Raahu is Uchcham in Rishabham and Kethu is Uchcham in Vrichigam and diagonally in the opposite houses they are Neecham.

☼ There is another school of thought that both Raahu and Kethu are Uchcham in Vrichigam and Neecham in Rishabha. Since both are Saayaa Grahas, they have no Aakshi house and the houses of their Uchcham and Neecham status is also uncertain.

☼ This aspect can decided only upon individual experiences. In my opinion, Vrichigam as Uchcham house and Rishabham as Neecham house for both Raahu and Kethu will be more appropriate. As said earlier, in their respective Uchcham (exalted) houses, the concerned Grahas are having their highest strength and in their respective Neecham (debilitated) houses, the concerned Grahas are nullified of their strength.