celestial equator
Heavenly zero latitude
The celestial equator is an imaginary great circle on the celestial sphere, directly above Earth's equator.
It divides the sky into northern and southern hemispheres, serving as a reference line for locating stars and other celestial objects.
The sun crosses the celestial equator at the spring and fall equinoxes.
Maximum spherical circumference
- projectionSomething that extends outward
- geocentricTreating our planet as center
- spherePerfectly round solid
- coordinate systemMethod for locating points
axis of rotation · perpendicular · tilt · obliquity · inclination · parallel · imaginary line · orbital plane
Spring's astronomical beginning
- autumnal equinoxEqual day and night
- March equinoxSpring's day-night balance
- September equinoxFall's equal day-night moment
- solsticeDay of maximum tilt
seasons · hemisphere · tropics · equinoctial
Angular distance from equator
- eclipticSun's apparent annual path
- hour angleAngular distance from meridian
- meridianPole-to-pole great circle
- star chartDiagram of celestial bodies
zenith · nadir · precession · epoch · sidereal · armillary sphere · astrolabe · astrometry
great circle
Maximum spherical circumference
- projectionSomething that extends outward
- geocentricTreating our planet as center
- spherePerfectly round solid
coordinate system · axis of rotation · perpendicular · tilt · obliquity · inclination · parallel · imaginary line · orbital plane
vernal equinox
Spring's astronomical beginning
- autumnal equinoxEqual day and night
- March equinoxSpring's day-night balance
- September equinoxFall's equal day-night moment
solstice · seasons · hemisphere · tropics · equinoctial
declination
Angular distance from equator
- eclipticSun's apparent annual path
- hour angleAngular distance from meridian
- meridianPole-to-pole great circle
star chart · zenith · nadir · precession · epoch · sidereal · armillary sphere · astrolabe · astrometry