hour circle

noun

Astronomy.

1. a great circle on the celestial sphere passing through the celestial poles and containing a point on the celestial sphere, as a star or the vernal equinox.

hour circle

noun

1. a great circle on the celestial sphere passing through the celestial poles and a specified point, such as a star

hour circle

1. A great circle passing through the poles of the celestial sphere and intersecting the celestial equator at right angles. An hour circle is equivalent to a meridian on Earth and is used in describing the position of a celestial body with respect to an observer's celestial meridian.

2. See more at hour angle

Word History and Origins

Origin of hour circle¹

First recorded in 1665–75