-as of [20 MARCH 2024]–
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*“equinox”*
*when [‘day’ / ‘night’] are of equal ‘duration(/time)’*
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(the word is derived from the latin aequinoctium, aequus (‘equal’) and nox (genitive noctis) (‘night’))
(an “equinox” occurs when the plane of the planet’s ‘equator’ passes the center of the sun)
(occurs twice each year, around “20 march” and “23 september”)
(n an ‘equinox’, ‘day’ and ‘night’ are of approximately equal duration all over the planet)
(they are not exactly ‘equal’, however, due to the ‘angular size’ of the ‘sun’ and ‘atmospheric refraction’)
(to avoid this ambiguity, the word equilux is sometimes (but rarely) used to mean a ‘day’ in which the durations of ‘light’ and ‘darkness’ are equal)
(“day” is usually defined as the period when ‘sunlight’ reaches the ‘ground’ in the absence of ‘local obstacles’)
(on the day of the ‘equinox,’ the center of the ‘sun’ spends a roughly equal amount of time above and below the horizon at every location on the ‘earth’, so ‘night’ and ‘day’ are about the same length)
(in reality, the ‘day’ is longer than the ‘night’ at an ‘equinox’)
(there are 2 reasons for this:)
(first, from the ‘earth’, the ‘sun’ appears as a disc rather than a ‘point’ of light, so when the center of the ‘sun’ is below the ‘horizon’, its upper edge is visible)
(‘sunrise’, which begins daytime, occurs when the top of the sun’s disk rises above the ‘eastern horizon’)
(as sun “rises in the ‘east’ (right?) and sets in the ‘west’ (left?))
(depends on which way you are facing)
(‘into’ or ‘out of’ the earth’s core)
(at that instant, the disk’s ‘center’ is still below the ‘horizon’)
(second, earth’s atmosphere refracts ‘sunlight’)
(as a result, an observer sees ‘daylight’ before the top of the sun’s disk rises above the ‘horizons’)
(even when the ‘upper limb’ of the ‘sun’ is 0.4 degrees below the ‘horizon’, its rays curve over the ‘horizon’ to the ‘ground’)
(in ‘sunrise’ / ‘sunset’ tables, the assumed ‘semidiameter’ (aka ‘apparent radius’) of the ‘sun’ is ’16 minutes’ of ‘arc’ and the ‘atmospheric refraction’ is assumed to be ’34 minutes’ of ‘arc’)
(their combination means that when the ‘upper limb’ of the ‘sun’ is on the ‘visible horizon’, its center is ’50 minutes’ of ‘arc’ below the ‘geometric horizon’, which is the ‘intersection’ with the ‘celestial sphere’ of a ‘horizontal plane’ through the ‘eye’ of the ‘observer’)
(these effects make the day about 14 minutes longer than the night at the equator and longer still towards the poles)
(the real equality of day and night only happens in places far enough from the equator to have a seasonal difference in day length of at least 7 minutes, actually occurring a few days towards the winter side of each equinox)
(the times of sunset and sunrise vary with the observer’s location (longitude and latitude), so the dates when day and night are equal also depend upon the observer’s location)
(at the equinoxes, the rate of change for the length of daylight and night-time is the greatest)
(at the ‘poles’, the ‘equinox’ marks the transition from 24 hours of ‘nighttime’ to 24 hours of ‘daylight’ (or ‘vice versa’))
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*👨🔬🕵️♀️🙇♀️*SKETCHES*🙇♂️👩🔬🕵️♂️*
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💕💝💖💓🖤💙🖤💙🖤💙🖤❤️💚💛🧡❣️💞💔💘❣️🧡💛💚❤️🖤💜🖤💙🖤💙🖤💗💖💝💘
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*🌈✨ *TABLE OF CONTENTS* ✨🌷*
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🔥🔥🔥🔥🔥🔥*we won the war* 🔥🔥🔥🔥🔥🔥