Editing Azimuth (section)

{{Short description|Horizontal angle from north or other reference cardinal direction}}
{{Other uses}}
{{Use dmy dates|date=July 2022}}
[[File:Azimuth-Altitude schematic.svg|right|thumb|The azimuth is the angle formed between a reference direction (in this example north) and a [[sightline|line]] from the observer to a point of interest projected on the same plane as the reference direction orthogonal to the [[zenith]].]]

An '''azimuth''' ({{IPAc-en|audio=en-us-azimuth.ogg|ˈ|æ|z|ə|m|ə|θ}}; from {{langx|ar|اَلسُّمُوت|as-sumūt|the directions}})<ref>The singular form of the noun is {{langx|ar|السَّمْت|as-samt|the direction}}.</ref> is the [[horizon]]tal [[Angle#Measuring angles|angle]] from a [[cardinal direction]], most commonly [[north]], in a local or observer-centric [[spherical coordinate system]]. 

Mathematically, the [[relative position]] [[vector (physics and mathematics)|vector]] from an observer ([[origin (mathematics)|origin]]) to a point of interest is [[graphical projection|projected]] [[perpendicular]]ly onto a [[reference plane]] (the [[horizontal plane]]); the angle between the projected vector and a reference vector on the reference plane is called the azimuth.

When used as a [[horizontal coordinate system|celestial coordinate]], the azimuth is the [[horizon]]tal direction of a [[star]] or other [[astronomical object]] in the [[sky]]. The star is the point of interest, the reference plane is the local area (e.g. a circular area with a 5&nbsp;km radius at [[sea level]]) around an observer on [[planetary surface|Earth's surface]], and the reference vector points to [[true north]]. The azimuth is the angle between the north vector and the star's vector on the [[horizontal plane]].<ref>{{cite Dictionary.com|azimuth}}</ref>

Azimuth is usually measured in [[degree (angle)|degrees]] (°), in the positive range 0° to 360° or in the signed range -180° to +180°. The concept is used in [[navigation]], [[astrometry|astronomy]], [[engineering]], [[map]]ping, [[mining]], and [[ballistics]].