What is "artificial 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.

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

   All the horizon round Invested with bright rays.
   --Milton.

2. (Astron.)

   1. 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.

   2. A plane parallel to the sensible horizon of a place, and passing through the earth's center; -- called also rational horizon or celestial horizon.

   3. (Naut.) The unbroken line separating sky and water, as seen by an eye at a given elevation, no land being visible.

3. (Geol.) The epoch or time during which a deposit was made.

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

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.

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

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.

   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.

Artificial \Ar`ti*fi"cial\, a. [L. artificialis, fr. artificium: cf. F. artificiel. See Artifice.]

1. Made or contrived by art; produced or modified by human skill and labor, in opposition to natural; as, artificial heat or light, gems, salts, minerals, fountains, flowers.

   Artificial strife Lives in these touches, livelier than life.
   --Shak.

2. Feigned; fictitious; assumed; affected; not genuine. ``Artificial tears.''
   --Shak.

3. Artful; cunning; crafty. [Obs.]
   --Shak.

4. Cultivated; not indigenous; not of spontaneous growth; as, artificial grasses.
   --Gibbon.

   Artificial arguments (Rhet.), arguments invented by the speaker, in distinction from laws, authorities, and the like, which are called inartificial arguments or proofs.
   --Johnson.

   Artificial classification (Science), an arrangement based on superficial characters, and not expressing the true natural relations species; as, ``the artificial system'' in botany, which is the same as the Linn[ae]an system.

   Artificial horizon. See under Horizon.

   Artificial light, any light other than that which proceeds from the heavenly bodies.

   Artificial lines, lines on a sector or scale, so contrived as to represent the logarithmic sines and tangents, which, by the help of the line of numbers, solve, with tolerable exactness, questions in trigonometry, navigation, etc.

   Artificial numbers, logarithms.

   Artificial person (Law). See under Person.

   Artificial sines, tangents, etc., the same as logarithms of the natural sines, tangents, etc.
   --Hutton.

n. (context aviation English) An instrument that displays the pitch and roll of an aircraft in flight by comparing its attitude to a gyroscopically-maintained indication of the flat horizon line.

n. a navigational instrument based on a gyroscope; provides an artificial horizon for the pilot [syn: gyro horizon, flight indicator]

Artificial Horizon is a compilation album of remixed tracks by rock band U2. It was released exclusively to subscribing members of U2.com, replacing Medium, Rare & Remastered. The remix CD is of a similar vein to the band's 1995 release Melon: Remixes for Propaganda, which was also released exclusively to fans. A triple-vinyl edition was released to the general public until 14 May 2010; this version included an MP3 for the Snow Patrol remix of the song " Unknown Caller".