Sun is king among navagraha (the nine planets) and it is a source of energy and life. It is a male planet and it represents father as well as ancestors. Looking at other characteristics/traits/significances of this planet; it represents overall immunity, energy, initiative, courage, confidence, leadership, authority, dominance, aggression, creativity, intelligence, magnetism, charisma, diplomacy, individualism, will power, eyesight, kings, heads of states, high ranked government officials and the ability to produce children in case of male natives; among many other things.
Sun rules Pitta (fire) element in body. Hence it controls the amount of energy or fire in body; though Mars and Ketu may also do the same. Natives who have weak Sun in their horoscopes may suffer from health issues caused due to lack of fire element. Poor digestion, laziness, lack of initiative, low confidence and lack of aggression are some of the problems that such natives may face. On the other hand, if Sun is strong in a horoscope, the native may witness good results related to digestion, initiative, aggression, confidence; and other likewise things.
In case Sun is very strong; and Mars and/or Ketu are also strong; the native may suffer because of too much fire element. Such native may face problems like too much aggression, overconfidence, impulsiveness, self-centeredness, heightened ego, acidity, muscle cramps, sleep disorders and ulcers among other things.
Natives influenced by strong Sun generally enjoy good health due to overall strong immunity. Such natives may tend to stay fit and they may not gain much extra weight. When strong Sun rises in the ascendant in a horoscope; the native may be average in height, dominant, strong, energetic, confident, authoritative, magnetic and charismatic. Such placement in the horoscope of a female native may make her have more masculine traits than feminine ones. Hence such female native may be more interested in conquering the world and in achieving great things through profession; than getting married and raising family.
Natives under the influence of strong Sun may be strong-headed and they may not give up on their ideas, concepts and decisions. Such natives may be quick to understand things and they may make quick decisions. Once such decisions are made, they may also be quick to implement them. It is difficult to make these natives reconsider their decisions; especially through pressure of any type. For this reason; such natives may be seen as arrogant and egoistic. However, they may reconsider their decisions if someone can provide them with better visions. In many cases, such natives may also be handled well through emotional strength. It means they may reconsider their decisions/actions for people they care for and love.
Male natives with strong Sun may be capable of producing strong and healthy children. Such children may also be intelligent and authoritative. Such natives tend to work more than average and in some cases; they may work a lot. Hence they may achieve more in professional sphere but they may witness problems related to health, family and peace of mind; in the long run. Some of these natives may simply exhaust themselves by engaging more and more in work; with little rest and relaxation. This result may be seen when Sun is strong; and Mars and/or Ketu are also strong in a horoscope.
Sun may be strong or very strong in Aries, Leo and Sagittarius; depending on its nakshatra and navamsha placements in these signs. Taking an example; it may be very strong when placed in the sign of Aries, in Aries, Leo or Sagittarius navamsha. On the other hand; it may be strong but not very strong when placed in Aries, Libra or Cancer navamsha; within the sign of Aries.
Sun may do well or very well in Taurus, Gemini, Virgo, Scorpio and Capricorn; depending on its nakshatra and navamsha placements in these signs. It may not do well in Cancer and Aquarius whereas it may perform poorly in Libra which is the sign of its debilitation. Here again, a lot depends on placements of this planet in various nakshatras and navamshas within these signs. Taking an example, Sun may do well in Leo navamsha of Pushya and Sagittarius navamsha of Ashlesha; within the sign of Cancer. However, it may perform poorly in Cancer navamsha of Punarvasu, Libra navamsha of Pushya and Aquarius navamsha of Ashlesha; within the sign of Cancer.
Looking at Libra; Sun may perform relatively better in Sagittarius navamsha of Swati and Aries navamsha of Vishakha; within this sign. On the other hand; it may witness maximum debilitation in Libra navamsha of Chitra, followed by Aquarius navamsha of Swati; within the sign of Libra.
Affliction to Sun from malefic planets may result in formation of various types of defects. Among them; Pitra Dosh and Grahan Yoga are the prominent ones. On the other hand, conjunction of benefic Sun with other benefic planets may result in formation of good yogas. Among them; Budhaditya Yoga is a prominent one.