Which direction is the nadir sensor oriented relative to Earth's surface?

• A. Upward toward space
• B. Sideways
• C. Downward toward Earth's surface
• D. Diagonally downward toward Earth

Answer: (C)

A nadir sensor is oriented downward toward Earth—the point on the surface directly beneath the aircraft or satellite. This straight-down, perpendicular alignment gives a direct line of sight to the ground, providing consistent ground scale and minimal distortion for imaging or sensing the surface. Looking upward toward space, sideways, or diagonally downward would not target the ground point directly beneath and would introduce perspective differences and distortion. So downward toward Earth's surface is the correct orientation.