equinoctial line
Definition
Noun:
* The celestial equator: The equinoctial line is the great circle on the celestial sphere that is exactly midway between the celestial poles. It is the projection of Earth's equator onto the imaginary celestial sphere.
Usage
The term equinoctial line is used in astronomy and geography to describe a fundamental reference line in the sky.
* The sun crosses the equinoctial line twice a year, marking the equinoxes.
* Astronomers use the equinoctial line as a primary coordinate for locating celestial objects.
Advanced Usage
- In celestial coordinate systems: The serves as the fundamental plane for the equatorial coordinate system, where declination is measured north or south from it.
- A star located on the
equinoctial linehas a declination of 0 degrees.
Variants and Related Words
- Celestial equator: This is the most common synonym for .
- Equinoctial circle: A less common but equivalent term.
- Equinoctial (adjective): Pertaining to an equinox or the celestial equator (e.g., equinoctial point, equinoctial colure).
Synonyms
- Celestial equator
- Equinoctial circle
Related Concepts (Not Phrasal Verbs or Idioms)
- Celestial sphere: The imaginary sphere onto which all celestial objects are projected.
- Celestial poles: The points in the sky directly above Earth's North and South Poles.
- Equinox: The time when the sun crosses the celestial equator, making day and night of approximately equal length.
Noun
-
the great circle on the celestial sphere midway between the celestial poles
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