the angle between two planes

The hour angle of a point is the angle between two planes: one containing Earth's axis and the zenith (the meridian plane), and the other containing Earth's axis and the given point (the hour circle passing through the point).

the angular distance

In astronomy, hour angle is defined as the angular distance on the celestial sphere measured westward along the celestial equator from the meridian to the hour circle passing through a point.

a component of the equatorial coordinate system

The hour angle (HA) is measured westward from the meridian and is a component of the equatorial coordinate system.

a musical performance generated by the movement of the sun

Hour Angle is a musical performance generated by the movement of the sun.

an expression of time

Observing the sun from earth, the solar hour angle is an expression of time, expressed in angular measurement, usually degrees, from solar noon.

longitude

Declination in astronomy is comparable to geographic latitude, projected onto the celestial sphere, and hour angle is likewise comparable to longitude.

a means of measuring the time since upper culmination

Hour angle may be considered a means of measuring the time since upper culmination, the moment when an object contacts the meridian overhead.

a measurement between 0° and 360°,

Sidereal hour angle is a measurement between 0° and 360°, indicating how far west a body is from an arbitrarily chosen point on the celestial sphere called the First Point of Aries.

the angle between you and the body that you have used for your sight

Local Hour Angle is the angle between you and the body that you have used for your sight, at the time of your sight.

the angular displacement of the sun east or west of the local meridian due to rotation of the earth on the earth's axis at 15° per hour with morning being negative and afternoon being positive

: The hour angle is the angular displacement of the sun east or west of the local meridian due to rotation of the earth on the earth's axis at 15° per hour with morning being negative and afternoon being positive.

1 turn/24 or 15°

1 Hour angle is 1 turn/24 or 15°.

The angle between the meridian plane of the observer and the meridian plane of a celestial object, measured from east to west

The angle between the meridian plane of the observer and the meridian plane of a celestial object, measured from east to west, is called the hour angle of the object.

angular distance earth has rotated in a day

Hour Angle : The hour angle is angular distance earth has rotated in a day.

the angle () between the observer's Galileosub-Jupiter meridian and the anti-sunward meridian HA() , measured in the jovian equatorial plane in the direction of planetary rotation

Local hour angle is the angle (HA) between the observer's (Galileo) sub-Jupiter meridian and the anti-sunward meridian, measured in the jovian equatorial plane in the direction of planetary rotation.

as the difference between noon and the desired time of the day

The hour angle is defined as the difference between noon and the desired time of the day.

the angle along the celestial equator from the observer's meridian

The Hour angle measures the angle along the celestial equator from the observer's meridian to the hour circle passing through the sun.

the longitudinal difference between the sub-lunar point and the point we consider

(The hour angle is basically the longitudinal difference between the sub-lunar point and the point we consider.)

their position

Originally conceived by the American aviator Charles Lindbergh, the Hour Angle was designed for aircraft pilots to precisely locate and understand their position during flight.

The spherical angle for N's vertexor the corresponding arc QQ′ of the equator Q′NQ, having the north pole, N, ,

The spherical angle Q′NQ, having the north pole, N, for N's vertex, or the corresponding arc QQ′ of the equator, is called the hour angle of the star

minutes, and seconds

A body's hour angle is measured in hours, minutes, and seconds, and corresponds to seconds's right ascension as measured with respect to the observer's meridian (which changes with time) rather than the vernal equinox (which is fixed on the celestial equator).