Past exam of the year 2 of the earth sciences (geology) course of the University of Oxford / 2022 / Paper 1 / 4 / a / Solution

Many optical land-mapping missions acquire daylight images in the midmorning, roughly 10–11 local solar time, using a Sun-synchronous orbit. This supplies substantial solar illumination while often avoiding the stronger afternoon convective cloud development. It also gives useful relief shadows without the very long shadows and weak illumination of sunrise. Repeated local-time viewing reduces illumination changes when comparing scenes.^[ref]

The time is a mission design choice, not a law applying to every optical satellite; afternoon acquisitions also exist. Sun-synchrony approximately fixes local solar time, not the same civil clock time everywhere, and seasonal solar-angle changes remain.