CELESTIAL MERIDIAN Meaning and
Definition
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The celestial meridian is a fundamental concept in astronomy and navigation that refers to an imaginary line running from due north to due south, passing through the zenith or overhead point of an observer. In essence, it is an imaginary great circle on the celestial sphere that divides it into two equal halves.
In astronomical terms, the celestial meridian is used as a reference point to measure the altitude or angular distance of celestial objects above or below it. This measurement is crucial for determining the positions of stars, planets, and other celestial bodies as they appear to cross or intersect the meridian during their apparent daily motion.
The celestial meridian holds great significance for celestial navigation as well. It provides a reference for determining a ship or observer's longitude by measuring the angular distance between the celestial object's meridian and the observer's meridian, known as the time sight. This angular difference corresponds to a certain amount of time, enabling mariners and navigators to calculate their position on the Earth's surface accurately.
In summary, the celestial meridian is an essential concept that allows astronomers and navigators to locate and measure the positions of celestial bodies accurately. It serves as a crucial reference point for observational and navigational purposes, facilitating the precise determination of altitude, longitude, and the calculation of various astronomical phenomena.
Etymology of CELESTIAL MERIDIAN
The word "celestial" comes from the Latin word "caelestis", which means "heavenly" or "divine". It is derived from the Latin word "caelum", meaning "sky" or "heaven".
The word "meridian" derives from the Latin word "meridianus", meaning "midday" or "noon". It is derived from the Latin word "meridies", which means "midday" or "noon", and is a combination of "medius" meaning "middle" and "dies" meaning "day".
Therefore, the term "celestial meridian" is a combination of "celestial", referring to something heavenly or divine, and "meridian", relating to a midday or middle point.
