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
Lisa's First Word promotion due to the 1984 Summer Olympics boycott by the Soviet Union, as happened to Krusty. At one point in the episode, Dr. Hibbert refers to Olympic gymnastic medalist Mary Lou Retton. In its original American broadcast, "Lisa's First Word" was watched by 28.6 million viewers, the most-watched episode of the season. It finished thirteenth in the ratings for the week of November 30 to December 6, 1992, with a Nielsen rating of 16.6. The episode was the highest-rated show on Fox that week. It acquired the highest national Nielsen rating of the show since the season two episode "Bart