Sun in Astrology
The Sun is said to signify the self (the soul). He also signifies the father of the person. This broadly means that matters relating to the self and father are to be judged from the position of the Sun in the horoscope. That is to say if somebody wants to know about the experiences, his father will have at a particular date, you as an astrologer, will look into his horoscope and note the position of the Sun from the horoscope and answer the query about the father.
In astrological language the same is explained as the Sun is Atmakaraka and Pitrukaraka (meaning the significator of soul and father).
Significator of Sun (Karkatatwa)
Among the planets, the Sun has the status of the king. Power and authority are with the Sun. Respiration, mouth, throat, spleen, conscience, intelligence, individuality, courage, paternal matters, government, devotion to God, leadership, ability to withstand suffering, immunity, fame, self-reliance, liberal attitude, honour, progressive qualities, trustworthiness etc. are all indicated by the Sun.
If the Sun is favourable and powerful in the horoscope the native will enjoy all the above qualities and effects. If the Sun is weak in the horoscope all the above aspects will be weak too and the results will be harmful to the above aspects. For example, a weak Sun in the horoscope indicates strained relation with the father, feeble-mindedness, trouble from government, ailments to chest, throat, spleen and other parts of the body signified by Sun, lesser immunity to withstand diseases, and cheating mentality etc.