celestial horizon

American  

noun

Astronomy.

1. horizon2b

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celestial horizon British  

noun

1. See horizon

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celestial horizon Scientific  

1. A great circle on the celestial sphere having a plane that passes through the center of the Earth at a right angle to the line formed by an observer's zenith and nadir. The celestial horizon divides the celestial sphere into two equal hemispheres based on the observer's location, with one hemisphere representing the half of the sky visible to the observer at that location and the other representing the half that is hidden from the observer below the Earth's horizon. The celestial horizon is used as the reference point in determining a celestial body's altitude.

2. Also called rational horizon

3. Compare sensible horizon

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Etymology

Origin of celestial horizon

First recorded in 1895–1900

Example Sentences

The Dip of the horizon at sea is the angular depression of the apparent sea 693 horizon, or circle bounding the visible ocean, below the apparent celestial horizon as above defined.

From Project Gutenberg

The plane of the celestial horizon is, of course, different for different positions of the observer on the earth.

From Project Gutenberg

The celestial horizon is the intersection of the celestial sphere by a plane passing through the center of the earth and perpendicular to the normal.

From Project Gutenberg

We have still to define a great circle of the celestial sphere that is of equal importance with the celestial equator and the celestial horizon.

From Project Gutenberg

On the celestial horizon are the north, east, south and west points.

From Project Gutenberg