For photographers to capture good pictures of their subjects, the lighting conditions must be taken into account and adjusted for accordingly. The same holds true for a satellite attempting to photograph another object in space: it must know the lighting conditions to adjust camera settings and position itself properly to take the best photograph. This thesis presents a photon mapping based algorithm to compute a physically accurate representation of the illumination of objects in orbit around the Earth, taking into account the effects that cause refraction in the atmosphere. I also discuss the assumptions that I have made to utilize the algorithm in an interactive 3D visualization tool, which I implemented to view the illumination on objects at arbitrary positions in space. Finally, I show that the photon mapping method offers improvements over simpler methods of computing illumination.