A terrestrial observer can see about 18% of the far side of the moon for a certain time. The reason lies in lunar librations – “wobble” of the moon relative to the terrestrial observer. Librations arise due to the ellipticity of the lunar orbit, the inclination of the Moon’s rotation axis to the plane of its orbit, and the Moon’s proximity to the Earth.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.