It happens every 29 years. Saturn stays in one sign for 2.5 years. Which is long period than other planets although it is known as a slow moving planet among all 9 planets.
Saturn transits to your natal Sun make you question whether you are satisfied or not with yourself and force you to make more efforts to correct all your past mistakes. Your romantic feelings and your love relationships also suffer a crisis so that you learn to truly reflect your inner being. Saturn represents limitations,being alone , setbacks, responsibility, and patience. It is gain through losses. It is our insecurities.
We should reap what we sow. We should delay gratification, cultivate patience, and become responsible. We should not take things for granted, and we have to become productive, useful people in some manner or else we will perish.
The first Saturn transit over the natal Sun signals the end of innocence. Actually, it signals the end of native ignorance too, if one is willing and able. The first Saturn transit over the natal sun signifies the first time in the life of a person that he or she becomes aware that he or she occupies a space within the larger world. Children who experience this may often come out wise beyond their years, if Saturn manifests as a person to whom the child unduly becomes responsible for. Teenagers may have some something manifest in their lives that suddenly robs them of their innocence, and adults who experience this transit for the first time tend to be, the shock of sudden responsibility, of having to realize their limits, can be worse when they are conditioned to think otherwise.
Saturn Transits to Natal Sun
It indicates the end of associations, but often, these are good things, as they are distractions from the real work one must be doing. They do often indicate a separateness from peers or from the family name, and can either be a desire to individuate or a desire to salvage it from the rubble heap. Saturn transits to the natal sun indicate a desire not to repeat the mistakes of the people who came before us and the work to be done in order to not do that again.
also it gives aloneness. Saturn teaches us that one doesn‘t need to approval of others to be valid; we are valid because we exist. Saturn teaches us to depart from those who no longer serve us, and to let go of people who need to travel elsewhere. It teaches us that we can weather emotional storms, as they too, pass.