As the earth sphere is divided into the Western & the Eastern hemispheres by the Prime Meridien ( the Greenwich Meridien ) so is the Celestial Sphere divided into Western and Eastern hemispheres by the Celestial Meridien. As the globe is divided into northern and southern hemispheres by the Equator, so is the Celestial Sphere divided into the nothern and southern hemispheres by the Celestial Equator.
The Four Major Mathematical Points of the Zodiac
In Astronomy the Eastern Horizon is called the Ascendant. 180 degrees from it is the Western Horizon called as the Descendant. The intersecting point where the Ecliptic cuts the Celestial Meridien is called the Meridien Cusp ( M C ) and 180 degrees from it is called the Imum Coeli ( I C ).
The Computation of Houses
First the longitude of the Ascendant is calculated by using the following formula
Tan L = Sin E
Cos E Cos w – Sin w Tan A
Where L is the Ascendant, E is the Right Ascension of East Point , w the Sun’s maximum declination and A – the latitude of the place. Once the Ascending degree is known , 180 degrees is subtracted to get the Descendant.
The MC is calculated by using the following formula
Tan K = Tan R / Cos w
Where is the longitude of the MC, R the Right Ascension of the Meridien Cusp and w the Sun’s maximum declination. 180 degrees deducted from the MC is the longitude of the IC.
These 4 are the Four Houses of the Zodiac. Ascendant is the Ist House, IC the Fourth, Descendant the Seventh and MC, the tenth.
We have said that each sign of the Zodiac is 30 degrees each. If the Ascending Degree is Pisces, then the Ascendant is Pisces, the IC is Gemini, the Descendant is Virgo and the MC, Sagittarius.
Rulership of Signs
Aries ruled by Mars
Equal House Division or Bhava Theory
Now we have got the longitudes of the Ascendant ( Udaya Lagna ) , the Descendant ( Astha Lagna), the MC ( Madhya Lagna ) & the IC ( Patala Lagna ).
The distance from the Ascendant and the IC is divided by 3 and we have the first Three Houses.
The distance from the IC and the Descendant is divided by 3 and we have the 4th,5th and 6th houses.
The distance from the Descendant and MC is divided by 3 and we have the 7,8th and 9th houses
The distance from the MC and Ascendant is divided by 3 and we have the 10,11 and 12th houses.
The Houses of the Zodiac and what they represent