If Bohr’s quantization postulate (angular momentum = nh/2π) is a basic law of nature, it should be equally valid for the case of planetary motion as well. Why then do we never speak of quantization of orbits of planets around the sun?
The quantization of the orbits of the planetary motions is not considered in the same manner as the Bohr's quantization postulates for the atoms because the value of the angular momentum in terms of the Plank's constant h will be of the order of 1070h. The high value of the angular momentum leads to the quantum levels of the order of 1070. The energy and the angular momentum for such high values of n will be comparatively very small which is not possible in case of the planets.
