In Vedic astrology a constant reference is made to the Navamsa occupied by planets and the Lagna-point. Both, the Rasi-chart and the Navamsa-chart are deemed equally important and therefore, consulted together. Whereas the Rasi-chart provides overall information regarding the location of planets and sensitive-points such as the Lagna, the latter provides vital information regarding their active quality and strength. A planet may be well-placed in the natal-chart Rasi-wise but its full effects may not materialise if its situation in the navamsa-chart is not supportive.
In Vedic astrology, Navamsa means one-ninth part of a Zodiac Sign. Navamsa literally means the "Ninth Division". Thus, each navamsa measures 3 degrees and 20 minutes in longitude or one-quarter of a Nakshatra (Constellation), and the Zodiac of Signs comprises 108 navamsas divided into four groups, 1) Mesha (Aries), Simha (Leo) and Dhanus (Sagittarius)– for which signs the navamsas are from Aries to Dhanus, 2) Vrishibha (Taurus), Kanya (Virgo) and Makara (Capricorn) – they are from Makara to Kanya, 3) Mithuna (Gemini), Tula (Libra) and Kumbha (Aquarius)– they are from Tula to Mithuna, 4) Kataka (Cancer), Vrishchika (Scorpio) and Meena (Pisces) – they are from Kataka to Meena; the Lagna (Ascendant)rising or the planet situated in the first navamsa of Chara rasis ("movable signs"), in the 5th navamsa of Sthira rasis ("fixed signs") and in the 9th navamsa of Dwisavbhava rasis ("common signs") will be in Vargottama and hence strong.