zenith distance

American  

noun

Astronomy.

1. the angular distance from the zenith of a point on the celestial sphere to the sphere, measured along a great circle that is perpendicular to the horizon; the complement of the altitude.

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Etymology

Origin of zenith distance

First recorded in 1695–1705

Example Sentences

This figured out the size of the earth with a percentage of error surprisingly small when we consider the rough means with which Eratosthenes measured the sun's zenith distance and the distance between the two stations.

From Project Gutenberg

Bradley had a zenith sector, and with this he observed with the greatest care the zenith distance of Gamma Draconis at every possible opportunity.

From Project Gutenberg

Form used in the computation of the zenith distance and azimuth of the moon.

From Project Gutenberg

But there is the disadvantage that the flexure of the transverse axis causes a variable collimation error depending on the zenith distance of the star to which it is directed; and moreover it has been found that in some cases the personal error of an observer is not the same in the two positions of the telescope.

From Project Gutenberg

Two extremely sensitive levels are attached to the telescope, which latter carries a micrometer in its eye-piece, with a screw of long range for measuring differences of zenith distance.

From Project Gutenberg