Celestial horizon

Celestial horizon
Horizon Ho*ri"zon, n. [F., fr. L. horizon, fr. Gr. ? (sc. ?) the bounding line, horizon, fr. ? to bound, fr. ? boundary, limit.] 1. The line which bounds that part of the earth's surface visible to a spectator from a given point; the apparent junction of the earth and sky. [1913 Webster]

And when the morning sun shall raise his car Above the border of this horizon. --Shak. [1913 Webster]

All the horizon round Invested with bright rays. --Milton. [1913 Webster]

2. (Astron.) (a) A plane passing through the eye of the spectator and at right angles to the vertical at a given place; a plane tangent to the earth's surface at that place; called distinctively the sensible horizon. (b) A plane parallel to the sensible horizon of a place, and passing through the earth's center; -- called also {rational horizon} or {celestial horizon}. (c) (Naut.) The unbroken line separating sky and water, as seen by an eye at a given elevation, no land being visible. [1913 Webster]

3. (Geol.) The epoch or time during which a deposit was made. [1913 Webster]

The strata all over the earth, which were formed at the same time, are said to belong to the same geological horizon. --Le Conte. [1913 Webster]

4. (Painting) The chief horizontal line in a picture of any sort, which determines in the picture the height of the eye of the spectator; in an extended landscape, the representation of the natural horizon corresponds with this line. [1913 Webster]

5. The limit of a person's range of perception, capabilities, or experience; as, children raised in the inner city have limited horizons. [PJC]

6. [fig.] A boundary point or line, or a time point, beyond which new knowledge or experiences may be found; as, more powerful computers are just over the horizon. [PJC]

{Apparent horizon}. See under {Apparent}.

{Artificial horizon}, a level mirror, as the surface of mercury in a shallow vessel, or a plane reflector adjusted to the true level artificially; -- used chiefly with the sextant for observing the double altitude of a celestial body.

{Celestial horizon}. (Astron.) See def. 2, above.

{Dip of the horizon} (Astron.), the vertical angle between the sensible horizon and a line to the visible horizon, the latter always being below the former.

{Rational horizon}, and {Sensible horizon}. (Astron.) See def. 2, above.

{Visible horizon}. See definitions 1 and 2, above. [1913 Webster]


The Collaborative International Dictionary of English. 2000.

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  • celestial horizon — Horizon Ho*ri zon, n. [F., fr. L. horizon, fr. Gr. ? (sc. ?) the bounding line, horizon, fr. ? to bound, fr. ? boundary, limit.] 1. The line which bounds that part of the earth s surface visible to a spectator from a given point; the apparent… …   The Collaborative International Dictionary of English

  • Celestial horizon — The celestial horizon, also called the rational horizon, is a great circle parallel to the horizon, the center of which is the center of the Earth.ee also*Celestial sphere …   Wikipedia

  • celestial horizon — noun the great circle on the celestial sphere whose plane passes through the sensible horizon and the center of the Earth • Syn: ↑horizon • Hypernyms: ↑great circle …   Useful english dictionary

  • celestial horizon — The great circle of the celestial sphere, equidistant from the zenith and the nadir. It is the intersection of the sensible and rational horizons at infinity. Its plane passes through the center of the earth …   Aviation dictionary

  • celestial horizon — Astron. See under horizon (def. 2b). [1895 1900] * * * …   Universalium

  • celestial horizon — celes′tial hori′zon n. astron. See under horizon 2), b) • Etymology: 1895–1900 …   From formal English to slang

  • Horizon — Ho*ri zon, n. [F., fr. L. horizon, fr. Gr. ? (sc. ?) the bounding line, horizon, fr. ? to bound, fr. ? boundary, limit.] 1. The line which bounds that part of the earth s surface visible to a spectator from a given point; the apparent junction of …   The Collaborative International Dictionary of English

  • Celestial sphere — [ celestial equator.] In astronomy and navigation, the celestial sphere is an imaginary rotating sphere of gigantic radius , concentric and coaxial with the Earth. All objects in the sky can be thought of as lying upon the sphere. Projected from… …   Wikipedia

  • Horizon (disambiguation) — Horizon is the line at which the sky and the earth s surface appear to meet.Horizon or horizons may also refer to:Business* Horizon Global, a corporation specializing in media compression technology, peer to peer video telephony, and video on… …   Wikipedia

  • horizon — /heuh ruy zeuhn/, n. 1. the line or circle that forms the apparent boundary between earth and sky. 2. Astron. a. the small circle of the celestial sphere whose plane is tangent to the earth at the position of a given observer, or the plane of… …   Universalium

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