Planets

1. Agni tattva (fiery element) is ruled by Mars. Sun also has the same nature.
2. Bhoo tattva (earthy element) is ruled by Mercury.
3. Vaayu tattva (airy element) is ruled by Saturn.
4. Aakaasa tattva (ethery element) is ruled by Jupiter.
5. Jala tattva (watery element) is ruled by Venus. Moon also has the same nature.

http://ponnadi.blogspot.com/search/label/tattva 

These rulerships throw light on the basic nature of planets. 

1. Being a fiery planet, Mars governs leadership, enterprise etc. 
2. Being an earthy planet, Mercury governs memory, logical abilities etc. 
3. Being an airy planet, Saturn governs wandering and free spirit. 
4. Being a watery planet, Venus governs imaginative and creative work. 
5. Being an ethery planet, Jupiter governs wisdom, intelligence and perceiving knowledge.