Sun is significator of steadiness, stability, constant, stillness, equilibrium. स्थिर तत्त्व
Moon is significator of movement, changeability, variable, adjustibility, चलायमान तत्त्व
Nodes (Rahu and Ketu) is significator of all types of forces and frictions, resistance or opposition. Both nodes forces are at opposite vector to each other. It is the force between two masses attraction or repulsion. आकर्षण- विकर्षण तत्त्व ।
If a thing is still it will remain still (Sun) and it the thing is in motion it will remain in motion (Moon) untill and unless forces (Nodes) are applied.
Just a thought..
Astrologer and Vastukar