Azimuth, << AZ uh muhth, >> is a measure along the horizon of the angle between an object and a reference point. The reference point is usually due north, and the angle is measured in a clockwise direction. An object that lies due east would have an azimuth of 90°. A wind of direction 270° is blowing from the west. Azimuth may also be measured counterclockwise from due south. In this case, an object of azimuth 135° would lie to the northwest. The reference point can be made even clearer by giving the direction as S 135° W.
The azimuth of an object above or below the horizon is found using an imaginary circle called a great circle. One such circle passes through the object from a point directly above the observer. The azimuth is measured from the point where this circle intersects the horizon. To locate the object, its altitude must also be known.
Surveyors use azimuth to help determine boundary points. Soldiers use it to direct artillery fire. Astronomers and navigators use it to locate objects in the sky. However, these people must also know the altitude to locate a star or other object in the sky. Azimuth once referred to objects in the sky and bearing to land objects. But these terms now mean the same thing.
