Illuminated objects are objects the reflect light to the eye, but they do not generate their own light. There are two categories of objects that the human eye can see: illuminated objects and luminous objects. A luminous object is an object that is capable of generating its own light.
The moon is an example of an illuminated object, while the sun is an example of a luminous object. The moon reflects the light from the sun, while the sun generates its own light. Without luminous objects, there would be no illuminated objects. The absence of luminous objects would mean that everything would be completely dark, and there would be no sight.