In the scientific community, the traditional concept has been formed that 'quantum mechanics is only applicable to microscopic systems, classical mechanics is only applicable to macroscopic systems, and the Schrödinger equation cannot be used to describe macroscopic objects'. Under the constraints of this traditional concept, there has been no attempt for a long time to establish and apply the Schrödinger equation of gravitational potential energy to describe the motion of the Earth. By replacing the potential energy in the Hamiltonian operator from electromagnetic interaction potential energy to gravitational interaction potential energy, the Schrödinger equation that can describe planetary motion was successfully obtained. Many examples provided can prove that classical mechanics and quantum mechanics are compatible. We can combine classical mechanics and quantum mechanics to describe the same system. For describing an object, mass size is no longer an important determining factor in choosing between classical mechanics and quantum mechanics methods. Establishing the Schrödinger equation for gravitational potential energy can prompt us to change our mindset and liberate our minds. The idea that classical mechanics and quantum mechanics are opposed to each other and should be mutually exclusive can be transformed into the idea that they coexist due to complementarity.