celestial pole
Học thuậtThân thiện
Definition
- Noun:
- One of two points of intersection of the Earth's axis and the celestial sphere: The celestial pole is either of the two imaginary points in the sky where the Earth's axis of rotation, indefinitely extended, intersects the celestial sphere. These are the north celestial pole and the south celestial pole.
Usage
- The term "celestial pole" is used in astronomy and navigation to describe fixed reference points in the night sky.
- It is a singular, countable noun.
Examples
- Noun:
- Polaris, the North Star, is located very close to the north celestial pole.
- Navigators in the Southern Hemisphere use the south celestial pole for orientation.
- The position of the celestial poles appears to change very slowly over thousands of years due to precession.
Advanced Usage
- "The pole star": Refers to a bright star located near a celestial pole, used for navigation.
- Because it lies near the celestial pole, Polaris appears almost stationary in the night sky.
Variants and Related Words
- North Celestial Pole (NCP): The point in the northern sky directly above Earth's North Pole.
- South Celestial Pole (SCP): The point in the southern sky directly above Earth's South Pole.
- Celestial Sphere: An imaginary sphere of arbitrarily large radius, concentric with Earth, on which celestial objects appear to be projected.
Synonyms
- Pole of the heavens: A less common synonym for celestial pole.
Related Concepts (Not Phrasal Verbs or Idioms)
- Celestial Equator: The great circle on the celestial sphere that is directly above Earth's equator, equidistant from the celestial poles.
- Declination: In the equatorial coordinate system, the angular distance of a celestial object north or south of the celestial equator, measured from the celestial poles.
Noun
- one of two points of intersection of the Earth's axis and the celestial sphere