vertical circle
- noun
- Specialized
- He used the vertical circle to calculate the exact time of the star's culmination.
Examples
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The star crossed the vertical circle at midnight, making it easy to determine its altitude.
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Astronomers observed the planet as it moved past the vertical circle through the zenith.
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The vertical circle is essential for understanding celestial navigation.
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Astronomers study the vertical circles for accurate star positioning.
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Astronomers used the vertical circle to determine the star's position as it reached its highest point in the sky.
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The vertical circle helps navigators identify the zenith, which is crucial for charting celestial bodies.
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Using a telescope, he tracked the comet as it passed the vertical circle, marking an important event in his observations.
Surface Forms
Morphology
The meaning is directly compositional: 'vertical' (pointing straight up/perpendicular) modifies 'circle' to indicate a circle oriented in a vertical plane. While the full astronomical definition adds technical detail (great circle, zenith), a B1 learner who knows both constituent words can infer the basic sense without prior exposure.
Etymology
The term vertical circle comes from sky watchers imagining a circle that stands straight up through the 'point above your head'. The word vertical shows it is upright and circle shows it goes all the way around. Astronomers used that upright circle to 'measure a star's height', so it means a large circle through the sky that goes up and down through the top point over you.