hour circle

American  

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.

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hour circle British  

noun

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

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hour circle Scientific  

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

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Etymology

Origin of hour circle

First recorded in 1665–75

Example Sentences

See Examples For:

hour circle

Turn the hour circle into a position where the pointer can describe a circle through "Mizar."

From The Boy Mechanic: Volume 1 700 Things for Boys to Do by Popular Mechanics Co.

Right ascension, corresponding to terrestrial longitude, is the angular distance of a heavenly body from the vernal equinox measured on the celestial equator eastward to the hour circle passing through the body.

From Astronomical Lore in Chaucer by Grimm, Florence M.

The hour circle A is half of a similar card with the hour marks divided into 20 minutes.

From The Boy Mechanic: Volume 1 700 Things for Boys to Do by Popular Mechanics Co.

To layout the hour circle, draw two parallel lines AB and CD, Fig.

From The Boy Mechanic: Volume 1 700 Things for Boys to Do by Popular Mechanics Co.

The Hour Angle of a star is the angle between its hour circle and the meridian.

From A Text-Book of Astronomy by Comstock, George C.