Equinox is the English translation of the Latin word „ Äquinoktium"
„Äquinoktium, "equal day and night", the time when the sun is at one of two opposite points on the celestial sphere, where the celestial and the ecliptic intersect at the beginning of spring and fall, the time when day and night are equally long."
This occurrence happens each year at two specific moments in time when there is a location on the earth's equator where the center of the sun can be observed to be vertically overhead, occurring around March 20/21 and September 22/23. On these two days the turning point takes place as light and darkness balance at these two moments before the equinox gets the upper hand again. In ancient cultures the equinox was synonymous for a turning point or new beginning.
Not only is the natural phenomenon interesting but the particular astronomical and mathematical awareness are fascinating. Did you know, for instance, that the Incas were already aware of precise earth movements and thanks to their great architectural abilities were able to construct masterpieces such as Machu Picchu? Certain stone formations were built in such a way, that during the Equinox Day (this term was not known back then) the sunlight would project on all mountain tops around Machu Picchu? The purpose of the temples were multi-faceted: proximity to the "Gods" or an exact measurement of harvest time and calendar days are only a few examples.
Mayan cultures also used this special day for their rituals and symbols. Buildings like the sun temple in Palenque or El Castillo in Chichen Itza are the most famous remaining ruins. If you have ever experienced this combination of form, style, function, philosophy, mathematics and geometry through the refracted light of the Mayan snake on March 21st (spring Equinox) or September 22nd (fall equinox) you will understand this.