Objects in space are illuminated by a single light source, and are not surrounded by atmosphere. This is similar to the most fundamentally basic raytraced scene

Objects in space are illuminated by a single light source, and are not surrounded by atmosphere. This is similar to the most fundamentally basic raytraced scenes. To contrast, objects on Earth are often illuminated by many light sources, by the light reflected off of other nearby objects, and even by the light reflected/refracted through the atmosphere the surrounds them. This is very challenging to reproduce in a raytraced scene; so what we are used to is something on the spectrum between realistic and oversimplified. An oversimplified render of a scene on Earth will have sharp shadows and lack the color reflected off of surrounding objects.