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The 24 pages that link to Celestial equator, each with the reason it gives.

• EclipticRelated: Its tilt relative to the ecliptic sets the Sun’s annual north–south motion.

• Right ascensionRelated: Right ascension is measured eastward along this reference circle.

• Orbital inclinationRelated: Many satellite inclinations are measured from Earth’s equatorial plane.

• Tropical yearRelated: The Sun’s crossings of this great circle mark the equinoxes.

• DeclinationRelated: This great circle is the zero point from which declination is measured.

• EquinoxRelated: The Sun crosses this projected circle at each equinox.

• Solar declinationRelated: Solar declination measures angular distance from this reference circle.

• Great circleBroader topic: It is a named great circle used to define celestial coordinates.

• Equatorial coordinate systemRelated: It is the zero line from which declination is measured.

• Precession of the equinoxesRelated: The equinoxes are intersections of this circle with the ecliptic, and the circle shifts with Earth's axis.

• Earth's axial tiltRelated: Its orientation expresses the tilt between Earth's equatorial plane and orbital plane.

• Sidereal timeRelated: It is the reference circle used to define right ascension and hour angle.

• Armillary sphereRelated: A prominent ring marks this reference circle on many armillary spheres.

• Hour angleRelated: It provides the standard circle along which hour angle is measured.

• SolsticeRelated: The Sun’s maximum and minimum declinations are measured relative to this circle.

• Equatorial mountRelated: Right ascension is measured along this circle, perpendicular to the mount’s polar axis.

• Celestial poleRelated: It lies halfway between the poles and crosses the sky at right angles to Earth’s axis.

• March equinoxRelated: The Sun crosses this projected line moving north at the March equinox.

• Celestial globeRelated: This reference circle divides the globe's northern and southern celestial hemispheres.

• September equinoxRelated: The Sun crosses this projected circle as the September equinox occurs.

• Southern celestial hemisphereRelated: This boundary defines which celestial positions belong to the southern half.

• Winter solsticeRelated: Solar declination is measured relative to this sky-coordinate line.

• Galactic planeCompared with: It is an Earth-based reference plane, not the Milky Way’s disk midplane.

• Astronomical nutationRelated: Its changing orientation provides a reference for specifying nutation.