The Kaal Sarp Yog is formed when all the planets are situated between Rahu and Ketu. Rahu is known as the head of a demon snake and Ketu is its tail. People having Kaal Sarp Dosha may perform specific rituals on Naag-Panchmi as well as install energized Kaal Sarp Yantra in their house to protect them from the evil effect of this yog.