Pronunciation: [pɹˈa͡ɪm vˈɜːtɪkə͡l] (IPA) 
The word "prime vertical" is spelled as /praɪm vəˈtɪkəl/. The first part of the word, "prime", is pronounced as /praɪm/, with a long "i" sound. The second part, "vertical", is pronounced as /vəˈtɪkəl/, with the stress on the second syllable and a short "i" sound. The word refers to a line of longitude that runs from the north point of the horizon to the zenith, and is used in astronomy and navigation.
The prime vertical is a term used in astronomy and celestial navigation to describe a specific circle on the celestial sphere. It refers to the semicircle that passes through both the north and south celestial poles and is perpendicular to the celestial equator. The prime vertical divides the celestial sphere into two equal hemispheres: the eastern and western hemispheres.
The concept of the prime vertical is important in celestial navigation because it provides a reference point for determining the azimuth or bearing of celestial objects. Azimuth is the horizontal angle measured clockwise from the north direction to the object, and it is used to determine the object's position relative to an observer on Earth. By measuring the angle between the prime vertical and the object, navigators are able to calculate the azimuth and thus accurately determine the object's location.
In addition to celestial navigation, the prime vertical is also utilized in astronomy for various calculations and observations. For instance, the prime vertical is one of the reference lines used to define the coordinates of stars and other celestial bodies. Astronomical observations are often described in terms of their altitude and azimuth, both of which are measured with respect to the prime vertical.
Overall, the prime vertical plays a critical role in celestial navigation and astronomy, providing a fixed reference line on the celestial sphere that aids in determining the position and placement of celestial objects.
In astron., the vertical circle which passes through the east and west points of the horizon.
Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874.
The term "prime vertical" consists of two words: "prime" and "vertical".
The word "prime" originates from the Latin word "primus", meaning "first" or "foremost". It was adopted into English in the late 14th century, and it is commonly used to denote something of highest quality, importance, or significance. It is also used in mathematics and other fields to represent a number that is divisible only by itself and one.
The word "vertical" comes from the Latin word "verticalis", which means "perpendicular" or "upright". It is derived from the Latin word "vertex", meaning "highest point" or "top". In English, "vertical" refers to something that is aligned with the force of gravity, pointing directly upwards or downwards.
