Zenith On the International Space Station, "zenith" and "nadir" are used instead of "up" and "down", referring to directions within and around the station, relative to the earth. Zenith The zenith is an imaginary point directly "above" a particular location, on the imaginary celestial sphere. "Above" means in the vertical direction opposite to the apparent gravitational force at that location. The opposite direction, i.e. the direction in which gravity pulls, is toward the nadir. The zenith is the "highest" point on the celestial sphere. The word "zenith" derives from an inaccurate reading of the Arabic expression (), meaning "direction of the
Highest unclimbed mountain the world is usually a major undertaking, lesser peaks, while still very formidable, simply get less attention than the taller ones, and instead these taller peaks are summited by parties following a new route or perhaps during the winter when conditions are generally more treacherous. Many mountains, in addition to their highest point or peak, will also have subsidiary subpeaks. Generally, the topographic prominence of a peak or subpeak, as well as the general topography, all come into consideration when determining whether such apexes are considered to be independent peaks or subpeaks. Although objective criteria have been proposed for distinguishing