The nine planets (navagraha – celestial bodies of universe in Sanskrit) mentioned in the Hindu astrology (astrology, not astronomy) are Surya (Sun), Chandra (Moon), Mangala (Mars), Budha (Mercury), Brihaspati (Jupiter), Shukra (Venus), Shani (Saturn), Rahu (North Lunar Node), and Ketu (South Lunar Node).
Sun and Moon are not planets. Mars and its reddish color can easily be seen with naked eyes. Mercury can be seen near the western horizon after sunset and easter horizon before sunrise with naked eyes. Jupiter is one of the brightest objects visible to the naked eye in the night sky. Venus is the second-brightest natural object in the night sky after the moon. Saturn can also be observed in the sky with naked eyes. Rahu and Ketu denote the points of intersection of the paths of the Sun and the Moon as they move on the celestial sphere.
Only five planets that are visible to the eyes are mentioned. Other planets are not mentioned, not even Earth!
No extraordinary stuff here! The concept of Hindu navagraha amazes only a person with a pseudoscientific temperament.