A point source is an idealized model of a light source. It is believed that a point source emits light uniformly in all directions, and its dimensions are much less than the distance to the illuminated surface. The stars can be considered a point source, the Sun is no longer there, and an incandescent lamp can be considered as such only at distances much larger than the lamp itself.
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.