Azimuth
Horizontal angle from north used in navigation and astronomy.
Azimuth is a horizontal angle measured from a cardinal direction, most commonly north, in a local or observer-centric spherical coordinate system. It is a fundamental concept used in navigation, astronomy, engineering, mapping, geodesy, mining, and ballistics.
- field
- Navigation, Astronomy, Geodesy, Engineering
- known_for
- Horizontal angle measurement from north in celestial and terrestrial coordinate systems
- etymology
- From medieval Arabic 'al-sumūt' meaning 'the directions'
Lore & Background
The word azimuth originates from medieval Arabic 'al-sumūt', meaning 'the directions', and entered late Medieval Latin in an astronomical context, particularly in the use of the Arabic version of the astrolabe. Its first recorded use in English is in the 1390s in Geoffrey Chaucer's 'A Treatise on the Astrolabe'. The first known record in any Western language is in Spanish in the 1270s in an astronomy book largely derived from Arabic sources, the 'Libros del saber de astronomía', commissioned by King Alfonso X of Castile.
Reader's Guide
Azimuth is a key coordinate in the horizontal coordinate system used in celestial navigation, where it is paired with altitude. In modern astronomy, azimuth is nearly always measured from the north. In land navigation, azimuth is usually denoted by alpha (α) and defined as a horizontal angle measured clockwise from a north base line or meridian. Today, the reference plane for an azimuth is typically true north, measured as 0° azimuth, though other angular units such as grad or mil can be used. Some navigation systems use south as the reference vector. The concept is also used for satellite dish installation.
Did You Know?
- Azimuth is derived from medieval Arabic 'al-sumūt', meaning 'the directions'.
- Its first recorded use in English is in the 1390s in Geoffrey Chaucer's 'A Treatise on the Astrolabe'.
- In the horizontal coordinate system, azimuth is one of two coordinates, the other being altitude.
Frequently Asked Questions
What is Azimuth?
Azimuth is a horizontal angle measured from a cardinal direction—most often north—within a local or observer-centric spherical coordinate system. It provides a consistent way to express bearing in both celestial and terrestrial frameworks.
Where does the word 'Azimuth' come from?
The term traces back to the medieval Arabic phrase 'al-sumūt,' meaning 'the directions.' This etymology reflects the concept's original purpose of denoting directional orientation.
Which fields rely on Azimuth?
Azimuth is a core measurement in navigation, astronomy, geodesy, engineering, mining, and ballistics. Any discipline that needs to specify a horizontal bearing relative to north draws on this concept.
Why is Azimuth important in mapping and navigation?
It gives observers a shared, relative angular reference for expressing horizontal direction, making it essential for plotting courses, locating celestial objects, and aligning survey measurements. Without a common angular baseline like azimuth, coordinating positions across different coordinate systems would be far more difficult.
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