Sun stands for power and authority. Sun (Surya) Yantra on Bhoj patra is an auspicious instrument use to appease the planet Sun ( Surya ). Sun symbolizes Atma Tatva and Agni (fire). If Sun is in malefic situation in horoscope of a person, Sun yantra is recommended to remove it's malefic effects. Weak Sun in Birth chart leads to problems related to Eye, Stomach, and Heart and weak bones.