Sun is the soul of the universe, he is the giver of life and light to the universe, he is the king of planets and the planetary kingdom. Sun mahadasha in astrology can be considered a great period of transformation from within. Sun being a huge fire ball burns everything which comes in contact with him, the placement of sun in any house will burn some of the signification of that house due to excess heat, though it is not always negative. The Sun mahadasha comes after Venus dasha and is of a very small duration among the entire planetary dashas spanning merely 6 years.
Sun mahadasha usually proves to be great for those who have sun placed in 1,3,5,9,10,11 houses. Sun is also good in upachaya houses being a malefic. The 10th house is the natural digbala of the sun as it is at the zenith in the sky in the afternoon. Sun placed in Fire signs will give much better results as compared to Earthy and Airy signs, It can be said to be comparatively weak in water signs as fire and water are opposite elements. Those who have Aries, Leo, Sagittarius sun placed in the above said houses under benefic influence will have excellent sun dasha leading to all round progress, such as name, fame, successs in career, politics, public life, honors from government, financial success, sun in 6th gives high positions in jobs though it would affect health matters. The planet and the lordship of planets associated with sun will get a boost in the mahadasha of sun. Sun associated with 5th lord will give excellent in education, success in competitive exams, excellent grades and fame due to education. The dasha of sun will give a great atma bala if sun is strong in the horoscope and give radiance in the personality of the concerned jataka.
An afflicted sun in the 6,8,12 houses or placed in debilitation in libra with bad aspects would prove to be very bad leading to defamation, failure, punishment from government, health troubles, heart troubles, eye troubles, loss of father or distress to father, enemity with bosses and people in high position. There will always be some or the other problem with government authorities with no success or very less success in any undertaken task. Placement of sun in the 7th house gives problems in marriage and poses a threat of separation if afflicted. When a jataka has a weak sun he is not able to influence people in spite of having good talents and skills.
In the sun mahadasha, antardashas of Sun, moon, mars, jupiter, mercury etc can prove to be excellent in sun mahadasha whereas that of Rahu,ketu and venus can be bad periods depending on the PAC with sun in the horoscope. The 6 years period of sun mahadasha can be an excellent period for those who aspire to reach heights and gain name, fame, position and financial success in life. Also read about the Venus mahadasha and Ketu mahadasha here.