The planet Saturn is a slow planet and takes 30 years to revolve once around the Sun. It means it passes through all the 12 rashis or moonsigns in 30 years. Thus Shani spends on an average of two and half years in each rashi or moonsign. Shani is the Rasi lord for Makara (Capricorn) and Kumbha (Aquarius), is exalted in Tula (Libra) and in his fall in Mesha (Aries).Mercury and Venus are considered friendly towards Saturn, while the Sun, Moon and Mars are considered enemies. Shani is the lord of three nakshatras Pushyami, Anuradha and Uttara Bhadrapada.The movement of Shani through the moonsigns has a lot of importance in the hindu astrology and horoscope predictions. The effect of Shani starts when it enters the previous rashi/moonsign to one's own birth rashi and stops when it leaves the rashi/moonsign after one's birth rashi. The total period of 7.5 years (2.5 x 3) is called Saadesaati or Shani Maha Dasa, and during this period the person faces lot of difficulties and troubles in life. This period teaches that person many things important in his life and makes him wiser.