1. An apparatus for pilot situational awareness, said apparatus being implemented on-board an aircraft, said apparatus comprising: a terrain image engine for calculating a location of the aircraft and for providing terrain data for the calculated location; a processor for processing the terrain data and for processing light source data to generate a synthetic image, the synthetic image representing an appearance, as viewed from a view point of a pilot of the aircraft, of the terrain data illuminated by an appearance of a light source of the light source data, the light source positioned generally proximal to the view point of the pilot of the aircraft; and a display for displaying the synthetic image, wherein the apparatus is a Global Positioning System-based system, wherein the apparatus is user-configurable such that at least one of the terrain image engine and the processor provides the light source data by calculating rays of light being emitted from a point generally proximal to the view point of the pilot to a terrain in a user-selected space, the user-selected space being selected from among a plurality of choices presented to the user, said choices including: a space into which the aircraft is flying, a space from which the aircraft has flown, a space below the location of the aircraft, and a space extended from a wing of the aircraft.