equinoctial point
Noun: 1. Either of the two points on the celestial sphere where the celestial equator and the ecliptic intersect: In astronomy, an equinoctial point is one of the two specific locations in the sky where the Sun's apparent annual path (the ecliptic) crosses the celestial equator. These points mark the beginning of astronomical spring and autumn.
The term "equinoctial point" is a technical term used primarily in astronomy and celestial navigation. It refers to a precise coordinate in space. * The vernal equinoctial point (or First Point of Aries) is where the Sun crosses the celestial equator moving northward, marking the March equinox. * The autumnal equinoctial point (or First Point of Libra) is where the Sun crosses the celestial equator moving southward, marking the September equinox.
- Noun:
- The position of an equinoctial point is not fixed; it slowly moves westward due to precession.
- Ancient astronomers carefully observed the Sun's passage through the vernal equinoctial point to calibrate their calendars.
- Celestial coordinates, such as right ascension, are measured from the vernal equinoctial point.
- Precession of the equinoxes: This is the gradual westward shift of the equinoctial points along the ecliptic over a cycle of approximately 26,000 years. This means the astrological "signs" no longer align with the actual constellations associated with the equinoctial points.
- Equinox (n): This is the or when the Sun is located at an equinoctial point, resulting in nearly equal day and night lengths globally. While related, "equinox" refers to the moment in time, whereas "equinoctial point" refers to the spatial coordinate.
- Vernal point: Another name for the vernal equinoctial point (First Point of Aries).
- First Point of Aries: The traditional name for the vernal equinoctial point.
- First Point of Libra: The traditional name for the autumnal equinoctial point.
- Equinox (when referring to the Sun's position at that point, though this is a slight contextual shift).
- There are no perfect common-language synonyms for this precise astronomical term.
- Line of equinoxes: The line connecting the two equinoctial points.
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(astronomy) either of the two celestial points at which the celestial equator intersects the ecliptic
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