Nachtseite
Nachtseite is a term used in German astronomy to denote the hemisphere of a planetary body that is not illuminated by its primary star, usually the Sun. It contrasts with the Sonnenseite, the day side that faces the star. The boundary between these hemispheres is the terminator, where illumination transitions to darkness and day-night effects are most pronounced.
In bodies with atmospheres, heat is transported from the day side to the night side by winds,
Studying the Nachtseite helps scientists understand thermal structure, heat transport, and climate dynamics of planets and
In German-language writing, Nachtseite is the standard term for this concept. It is widely used in textbooks,