Hour circle Meaning, Definition & Usage

  1. noun a great circle on the celestial sphere that passes through both celestial poles

WordNet

Definitions
  1. . (Astron.) (a) Any circle of the sphere passing through the two poles of the equator; esp., one of the circles drawn on an artificial globe through the poles, and dividing the equator into spaces of 15°, or one hour, each. (b) A circle upon an equatorial telescope lying parallel to the plane of the earth's equator, and graduated in hours and subdivisions of hours of right ascension. (c) A small brass circle attached to the north pole of an artificial globe, and divided into twenty-four parts or hours. It is used to mark differences of time in working problems on the globe.

Webster 1913