Antisolar point

The antisolar point is the imaginary point on the celestial sphere exactly opposite the Sun from the viewpoint of an observer. This means that the antisolar point lies above the horizon when the Sun is below it, and vice versa. On a sunny day, the antisolar point can be easily found: It is located at the shadow of one's head. Like the zenith and nadir, the antisolar point does not have a fixed position in three dimensional space, but is defined in relation to the observer: Each observer has their own antisolar point, which moves along with them as they change position.