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hour angle
hour anglen. Abbr. ha The angular distance, measured westward along the celestial equator, between the celestial meridian of the observer and the hour circle passing through a celestial body.hour angle n (Astronomy) the angular distance along the celestial equator from the meridian of the observer to the hour circle of a particular celestial body hour′ an`gle
n. the angle, measured westward through 360°, between the celestial meridian of an observer and the hour circle of a celestial body. [1830–40] Thesaurus| Noun | 1. | hour angle - the angular distance along the celestial equator from the observer's meridian to the hour circle of a given celestial bodydistance - the property created by the space between two objects or points | | 2. | hour angle - (astronomy) the angular distance of a celestial point measured westward along the celestial equator from the zenith crossing; the right ascension for an observer at a particular location and time of dayHAastronomy, uranology - the branch of physics that studies celestial bodies and the universe as a wholeangular distance - the angular separation between two objects as perceived by an observer; "he recorded angular distances between the stars" |
Translationshour angle
hour angle, in astronomy, a coordinate in the equatorial coordinate systemequatorial coordinate system,
the most commonly used astronomical coordinate system for indicating the positions of stars or other celestial objects on the celestial sphere. The celestial sphere is an imaginary sphere with the observer at its center.
..... Click the link for more information. . The hour angle of a celestial body is the angular distance, expressed in hours, minutes, and seconds (one hour equals 15 degrees), measured westward along the celestial equator from the observer's celestial meridian to the hour circlehour circle,
in astronomy, a secondary axis in the equatorial coordinate system. The hour circle of a celestial body is the great circle on the celestial sphere that passes through both the body and the north celestial pole.
..... Click the link for more information. of the object being located. The hour angle is used in measuring astronomical time; local sidereal timesidereal time
(ST), time measured relative to the fixed stars; thus, the sidereal day is the period during which the earth completes one rotation on its axis so that some chosen star appears twice on the observer's celestial meridian.
..... Click the link for more information. is equal to the hour angle of the vernal equinox.hour angle (HA) Symbol: t. The angle measured westward along the celestial equator from an observer's meridian to the hour circle of a celestial body or point. It is usually expressed in hours, minutes, and seconds from 0h to 24h. It is thus measured in the same units but in the opposite direction to right ascension. The angle measured eastward along the equator from the meridian is sometimes called the meridian angle. Due to the daily apparent rotation of the celestial sphere, a celestial body's hour angle increases daily from 0h at the meridian; after six hours the hour angle is 6h and 24 hours later the celestial body again crosses the meridian. See also sidereal hour angle.hour angle[′au̇r ‚aŋ·gəl] (astronomy) Angular distance west of a celestial meridian or hour circle; the arc of the celestial equator, or the angle at the celestial pole, between the upper branch of a celestial meridian or hour circle and the hour circle of a celestial body or the vernal equinox, measured westward through 360°. hour angle The angular distance west of a celestial meridian or hour circle; the arc of the celestial equator, or the angle at the celestial pole, between the upper branch of a celestial meridian or hour circle and the hour circle of a celestial body or the vernal equinox, measured westward through 360°. At any instant, hour circles are coincident with particular celestial meridian. There are three types of hour angles: sidereal, Greenwich, and local. The sidereal hour angle is the angle of the celestial pole between the celestial meridian of the first point of the Aries and the celestial meridian of the body, measured westward from the celestial meridian of the first point of Aries. The Greenwich hour angle is the arc of the equatorial measured westward through
360° measured from the celestial meridian of the Greenwich to the hour circle of the body. The local hour angle is the angle at the celestial pole measured westward from the observer's meridian to the celestial meridian of the body.AcronymsSeeheadachehour angle
Synonyms for hour anglenoun the angular distance along the celestial equator from the observer's meridian to the hour circle of a given celestial bodyRelated Wordsnoun (astronomy) the angular distance of a celestial point measured westward along the celestial equator from the zenith crossingSynonymsRelated Words- astronomy
- uranology
- angular distance
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