Celestial equator
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The celestial equator is the great circle of the imaginary celestial sphere on the same plane as the equator of a planet, by convention generally Earth. By extension, it is also a plane of reference i
Celestial equator in relation to the galactic and ecliptic planes
Ecliptic
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The ecliptic or ecliptic plane is the apparent path of the Sun on the celestial sphere, resulting from Earth's orbit around the Sun. It was a central concept in a number of ancient sciences, providing
A depiction of the early Solar System's protoplanetary disk from which Earth and other Solar System bodies were formed
A dark sky view, showing the difference in inclination of the galactic plane of the Milky Way to the not much inclined to each other orbital planes of the Solar System planets incl. the ecliptic, which is illuminated by the outlined zodiacal light and flanked by a meteor shower
At Earth's poles the Sun appears at the horizon only and all day around equinox, marking the change between the half year long polar night and polar day. The picture shows the South Pole right before March equinox, with the Sun appearing through refraction despite being still below the horizon.