right ascension

right ascension
the arc of the celestial equator measured eastward from the vernal equinox to the foot of the great circle passing through the celestial poles and a given point on the celestial sphere, expressed in degrees or hours.
[1585-95]

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      in astronomy, the east–west coordinate by which the position of a celestial body is ordinarily measured; more precisely, it is the angular distance of a body's hour circle east of the vernal equinox, measured along the celestial equator. It is often expressed in units of time rather than degrees of arc. Right ascension and declination define the position of a celestial object. The symbol for right ascension is the Greek letter α (alpha). See also hour angle.

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  • Right ascension — (abbrev. RA; symbol α) is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. The other coordinate is the declination.ExplanationRA is the celestial equivalent of… …   Wikipedia

  • Right ascension — Right Right (r[imac]t), a. [OE. right, riht, AS. riht; akin to D. regt, OS. & OHG. reht, G. recht, Dan. ret, Sw. r[ a]tt, Icel. r[ e]ttr, Goth. ra[ i]hts, L. rectus, p. p. of regere to guide, rule; cf. Skr. [.r]ju straight, right. [root]115. Cf.… …   The Collaborative International Dictionary of English

  • Right ascension — Ascension As*cen sion, n. [F. ascension, L. ascensio, fr. ascendere. See {Ascend}.] 1. The act of ascending; a rising; ascent. [1913 Webster] 2. Specifically: The visible ascent of our Savior on the fortieth day after his resurrection. ( Acts i.… …   The Collaborative International Dictionary of English

  • right ascension — ► NOUN Astronomy ▪ position measured along the celestial equator, expressed in hours, minutes, and seconds …   English terms dictionary

  • right ascension — n. Astron. the angular distance of the hour circle of a celestial body from the vernal equinox, measured eastward along the celestial equator and expressed in degrees (from 0 to 360) or, more commonly, in hours (from 0 to 24), minutes, and… …   English World dictionary

  • right ascension — Refraction Re*frac tion (r?*fr?k sh?n), n. [F. r[ e]fraction.] 1. The act of refracting, or the state of being refracted. [1913 Webster] 2. The change in the direction of ray of light, heat, or the like, when it enters obliquely a medium of a… …   The Collaborative International Dictionary of English

  • right ascension — noun (astronomy) the equatorial coordinate specifying the angle, measured eastward along the celestial equator, from the vernal equinox to the intersection of the hour circle that passes through an object in the sky; usually expressed in hours… …   Useful english dictionary

  • right ascension — right′ ascen′sion n. astron. the arc of the celestial equator measured eastward from the vernal equinox to the foot of the great circle passing through the celestial poles and a given point on the celestial sphere, expressed in degrees or hours • …   From formal English to slang

  • right ascension — noun Date: 15th century the arc of the celestial equator between the vernal equinox and the point where the hour circle through a given body intersects the equator reckoned eastward commonly in terms of the corresponding interval of sidereal time …   New Collegiate Dictionary

  • Right ascension — …   Википедия

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