phaseangle

Definition: phaseangle: The angle between the Sun, target, and a spacecraft. Low-phase is a small angle between the Sun, target, and the spacecraft. A low phase angle provides high sun illumination, similar to taking a picture from a high altitude at noon (with the sun directly overhead). Such illumination emphasizes the brightness contrasts of light and dark areas. High-phase is a large angle between the Sun, target, and the spacecraft. A high phase angle provides low sun illumination, similar to taking a picture from a high altitude at sunset or sunrise. Such illumination emphasizes the topography of the terrain.