Azimuth

Azimuth, in astronomy, a horizontal coordinate used, in combination with altitude, to describe an object’s apparent position in the sky at a given moment. Azimuth is expressed in degrees (°), minutes (′), and seconds (′′) of arc, increasing clockwise from due north at azimuth 000°, to due east (090°), due south (180°), and so on. As the Earth rotates on its axis, stars and other bodies in the sky increase in azimuth. In the northern hemisphere, celestial objects reach their highest altitude above the horizon when their azimuth reaches 180°. Navigators sometimes refer to azimuth as bearing; the terms can be regarded as interchangeable. In the equatorial coordinate system, right ascension is equivalent to azimuth, and declination to altitude.