On Earth, the sky is blue due to the fact that the scattering of sunlight by air molecules is selective: the blue part of the spectrum is scattered more than the red. There is no atmosphere on the moon and therefore there is almost no light scattering. On Mars, due to frequent dust storms, the atmosphere is saturated with the smallest dust particles, which, like the soil, have a red color.
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.