Which word can be used interchangeably with "zenith" in astronomy?

In the context of astronomy, "zenith" refers to the point in the sky that is directly above an observer. The term that can be used interchangeably with "zenith" is "apogee," which describes the point in an orbit of an object where it is farthest from the center of the Earth. Although they refer to different specific points (apogee in relation to an orbit and zenith in relation to an observer's viewpoint), both terms describe positions at the extreme of a certain context in a celestial framework.

Although terms like "nadir," "altitude," and "meridian" are also relevant in discussing positions in astronomy, they do not serve as direct synonyms for "zenith." The "nadir" indicates the point directly opposite the zenith, effectively at the lowest point in the sky from the observer's perspective, while "altitude" refers to the angle or height of an astronomical object above the observer's horizon. The "meridian" is a vertical line that represents the highest point an object reaches in the sky at a given time but does not replace "zenith" as a term. Thus, "apogee" is the most contextually appropriate word to relate to "zenith