Rishi Parashar states :
Madhupingaladriksuryashchaturastah shuchirdwi I
pittaprakratiko dhimaan pumaanalpakacho dwij IIsurya-z

“The Sun has honey colored eyes ,square body; he is of clean habits ; bilious in nature ; intelligent and with scanty hair “.
Sun is considered as the king of all the planets in vedic astrology .He is the primary significator of soul and gets exalted in aries, in ashwini nakshtra which belongs to ketu , the mokshakarak. This indicates that primary objective of all the souls is to attain moksha. At sunrise sun is in the lagna, during midday sun goes to 10th house , at sun set sun is in the 7th house and at midnight in the 4th house. Thus during the day, the sun is actually moving in the reverse direction in the chart. This indicates that we all are under the influence of maya (rahu) in this world .
Sun is a male planet and is cruel ( kroora ) in nature . He is basically satwik in nature and hence should not be mistaken as a malefic planet. Sun is dignified , have purity of thoughts,honourable and generous with good manners. He is very punctual and is the source of wealth and prosperity. The twelve signs in a chart are also called as dwadasha aaditya indicating that Sun is the source of everything .
Sun is the siginificator of lagna and indicate vitality, fame, intelligence and self respect. Sun represents the basic framework in all the fields just as it is the central planet in the solar system. In the body, Sun represents the skeletal system , the primary frame of the body and is the significator of bones. If Sun is strong in the chart then the native is generally blessed with strong bones . Sun is also the significator of father and rules all the places that are meant for worship .
Sun is the fiery planet and is strong in the southern direction as it gets digbala in 10th house. When sun is in digbala the native is said to be blessed by Indra and worshiping Indra with proper mantras can bestow good material and professional prosperity to the native with digbali surya . The adi devata of sun is agni or vahnni while the prtyadi devata is shiva . If sun is weak or malefic in the chart then worshiping Lord Shiva can ward off the evil effects of such a placement of sun.
Since Sun is the king of the nine planets, it is said that worshiping Surya ,offering water to him and reciting Surya ashtakam can actually remove a lot of navagrah doshas in the chart.