Antisolar point anthelic point, such as the anthelion, Wegener arcs, Tricker arcs and the parhelic circle itself. Antisolar point The antisolar point is the abstract point on the celestial sphere directly opposite of the Sun from an observer's perspective. 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 within the shadow of the observer's head. Like the zenith and nadir, the antisolar point is not fixed in three-dimensional space, but is defined relative to the observer. Each observer
Nadir also used figuratively to mean the lowest point of a person's spirits, or the quality of an activity or profession. In medicine, the term nadir is used to represent the lowest level of something being measured; for example, of a blood cell count while a patient is undergoing chemotherapy, or of a blood glucose level after a baby is born. A diagnosis of neutropenic nadir after chemotherapy typically lasts 7–10 days, and a newborn's blood sugar normally reaches its nadir around 2 hours after birth. The word also refers to the downward-facing viewing geometry of an orbiting satellite, such as