Navagraha (nine graha) include the Sun, the Moon, Mars, Mercury, Jupiter, Venus, Saturn, Rahu and Ketu.
But interestingly, the Sun is not a planet and it is a star, Moon (astronomical body),Rahu (Northern lunar node) and Ketu (Southern lunar node). Technically those are not planets right?
Can any Scriptures describe about why Sun, Moon, Rahu and Kethu are called Navagraha?
Edit: We have 9 planets in our solar system in which why only 5 planets? Why Earth not in the part if it? then still why Hindu astrologers draw the birth charts of individuals based upon the graha position at the time of their birth.