Angular distance


Angular distance

In mathematics (in particular geometry and trigonometry) and all natural sciences (including astronomy, geophysics, etc), the angular distance (angular separation, apparent distance, or apparent separation) between two point objects, as observed from a location different from either of these objects, is the size of the angle between the two directions originating from the observer and pointing towards these two objects. Angular distance (or separation) is thus synonymous to angle itself, but is meant to suggest the (often large or unknown) linear "distance" between these objects (for instance stars, as they are observed from Earth).

Measurement

Since the angular distance (or separation) is conceptually identical to an angle, all three are measured in the same units, such as degrees or radians, using instruments such as goniometers or optical instruments specially designed to point in well-defined directions and record the corresponding angles (such a telescopes).

Equation

In order to calculate the angular distance in arcsecond for binary star system, extrasolar planets, solar system objects and other astronomical objects, we use orbital distance (semi-major axis) in AU divided by stellar distance in parsecs.

: heta = frac {a}{D}

See also

* Angular mil
* Grad (angle)
* Hour angle
* Central angle


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  • Angular distance — Angular An gu*lar, a. [L. angularis, fr. angulus angle, corner. See {Angle}.] 1. Relating to an angle or to angles; having an angle or angles; forming an angle or corner; sharp cornered; pointed; as, an angular figure. [1913 Webster] 2. Measured… …   The Collaborative International Dictionary of English

  • Angular distance — Distance Dis tance, n. [F. distance, L. distantia.] 1. The space between two objects; the length of a line, especially the shortest line joining two points or things that are separate; measure of separation in place. [1913 Webster] Every particle …   The Collaborative International Dictionary of English

  • angular distance — kampinis atstumas statusas T sritis fizika atitikmenys: angl. angular distance; angular separation vok. Winkelentfernung, f rus. угловое расстояние, n pranc. distance angulaire, f …   Fizikos terminų žodynas

  • angular distance — kampinis atstumas statusas T sritis Standartizacija ir metrologija apibrėžtis Atstumas, išreikštas kampo matavimo vienetais. atitikmenys: angl. angular distance vok. Winkelentfernung, f rus. угловое расстояние, n pranc. distance angulaire, f …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • angular distance — noun the angular separation between two objects as perceived by an observer he recorded angular distances between the stars • Hypernyms: ↑angle • Hyponyms: ↑latitude, ↑longitude, ↑declination, ↑celestial latitude, ↑ …   Useful english dictionary

  • angular distance — Apparent distance, distance as measured by an angle …   New dictionary of synonyms

  • angular distance — /ˌæŋgjələ ˈdɪstəns/ (say .anggyuhluh distuhns) noun the distance between two bodies in terms of the angle subtended by them at the point of observation …   Australian English dictionary

  • angular distance — the aperture of the angle made at the eye by lines drawn from the eye to two objects …   Medical dictionary

  • Angular — An gu*lar, a. [L. angularis, fr. angulus angle, corner. See {Angle}.] 1. Relating to an angle or to angles; having an angle or angles; forming an angle or corner; sharp cornered; pointed; as, an angular figure. [1913 Webster] 2. Measured by an… …   The Collaborative International Dictionary of English

  • Angular aperture — Angular An gu*lar, a. [L. angularis, fr. angulus angle, corner. See {Angle}.] 1. Relating to an angle or to angles; having an angle or angles; forming an angle or corner; sharp cornered; pointed; as, an angular figure. [1913 Webster] 2. Measured… …   The Collaborative International Dictionary of English