After the Trinity (Brahma, Vishnu, Siva) the Navagrahas (including Surya) have the maximum importance in Hindu Rituals. They are considered in all Hindu traditions as important steps towards creation of life on the earth.

All the nine grahas (planets) viz Sun, Moon, Mars, Mercury, Jupiter, Venus, Saturn, Rahu (Sanke's head) and Ketu (Snake's tail) give us pleasure and serenity and remove obstacles from our way. The names of the seven bodies (Sun, Moon, Mars, Mercury, Jupiter, Venus, Saturn) are still connected, in some languages, with the seven days of the week.

In astrology, great importance is placed on the positions of the various planets in the twelve constellations of the zodiac, the belt around the sky in which the movements of Sun, Moon and planets are confined.  All astrology is totally based on the planetary movements and its effect on human beings. 

The picturisation of the Navagrahams & their vahanas differs from source to source.