Quantization Rule for Planetary Motion?

[Mahasweta]

according to sommerfield quantization rule "for any physical system in which the co ordinates are periodin functions of time,there exist a quantum condition for each coordinate(e.g in bohrs heory angular momentum is quantised)" then why there is no quantization rule in planetary motion but the coordinates in this system is also periodic functions of time?

 

[Nugatory]

why there is no quantization rule in planetary motion?

There would be, but the gaps between adjacent quantum levels are so small relative to the mass energy, and momentum of the planet, and there are so many of them, that we can treat the motion of planets as if it is continuous.