The 12 Rashis: India's Zodiac 12 രാശികൾ: ഇന്ത്യയുടെ രാശിചക്രം

The 12 Rashis divide the ecliptic into 12 equal sections of 30° each - Mesha (Aries), Vrishabha (Taurus), Mithuna (Gemini), Karka (Cancer), Simha (Leo), Kanya (Virgo), Tula (Libra), Vrishchika (Scorpio), Dhanu (Sagittarius), Makara (Capricorn), Kumbha (Aquarius), Meena (Pisces). These look identical to the Western zodiac signs - the names even match. But there is a crucial difference.

Indian astronomy uses the sidereal (Nirayana) zodiac - the zero point is fixed to distant stars. Specifically, the star Spica (Chitra) is defined to be at exactly 180° on the sidereal ecliptic. This means the Rashi grid is nailed to the actual stars and never drifts. Western astronomy uses the tropical (Sayana) zodiac - the zero point is the vernal equinox, which slowly drifts because of precession (Earth's axis wobbles like a spinning top, completing one cycle in ~26,000 years).

Right now, the two systems are about 24° apart. This gap is called the Ayanamsha. It grows by roughly 1° every 72 years. This is why your Indian Rashi and Western zodiac sign are often different - typically shifted by one sign. It also explains why Makar Sankranti (Sun enters Makara in the sidereal system) falls about 23 days after the winter solstice (which is the tropical event).

Think of Rashis and Nakshatras as two grids overlaid on the same sky: Rashis are the coarse grid (12 boxes of 30°) and Nakshatras are the fine grid (27 boxes of 13°20'). Each Rashi contains exactly 2¼ Nakshatras.