Why does an artificial Earth satellite (AES) not disappear instantly when it enters the Earth’s shadow?

Two factors play a role here: the weakening of the sun’s light due to an increase in the optical depth of the atmosphere and the presence of the Earth’s penumbra.

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.