Kaal Sarp Dosha
When all the prime planets (Sun, Mercury, Venus, Mars, Jupiter, Saturn, Moon) are placed between Rahu & Ketu the kundali is said to have the Kalsarpa Yoga. This yoga is considered harmful by some astrologers. According to this theory all these planets then come under the influence of Rahu and Ketu, and the person sees a lot of struggle and challenges in his life. At the same time the Kalsarpa Yoga multiplies the opportunities along with the threats and may give great rise to the person.