There are 9 planets, which, according to Hindu Astrology, have powerful influence on the earth.  These are:

1. Sun        2. Moon

3. Mars        4. Mercury

5. Jupiter        6. Venus

7. Saturn        8. Rahu

9. Ketu

The last two, i.e. Rahu and Ketu are not exactly planets, as they do not have physical bodies.  They are called shadowy planets.  North Point, where the Moon crosses the Ecliptic, is known as Rahu and South Point is known as Ketu.  They are 180° apart from each other.  They are the nodes of Moon.

All the planets (except Rahu and Ketu) not only revolve on their own axis but also round the Sun.  Moon is the nearest to the Earth and Saturn the most distant from the Earth.

Sun and Moon are never in retrograde motion, i.e. they do not move backwards.  Rahu and Ketu always move backwards.  The other planets have both direct and retrograde motion.