I have written and published on this topic before. It is good to remember our connections with Mother Earth, our solar system and the cosmos.
I know your calendar calls it something else, as if it is a meaningless Hallmark holiday, but mankind has paid attention to these things throughout our history. They are significant in the real world. So I repost most of what I put up last year at this time.
It is not a Hallmark Holiday or made-up event. In cultures past, who paid attention to natural rhythms, the autumn equinox was a big deal. Today, day and night are of equal length. Harvest festivals and putting produce up for the winter are major parts of this natural rhythm in societies who do not get their food from grocery stores and restaurants.
Your wall calendars and media will call today “first day of autumn” or some other trivializing phrase. Just don’t confuse it with other fabricated events on your pre-printed calendar. The Cosmos says this one is real.
The days have been getting shorter since the summer solstice, and will continue shrinking until the winter solstice December 21st.
The equinoxes are the only times when the solar terminator (the “edge” between night and day) is perpendicular to the equator. As a result, the northern and southern hemispheres are equally illuminated. The word comes from Latin equi or “equal” and nox meaning “night”.
In other words, the equinoxes are the only times when the subsolar point is on the equator, meaning that the Sun is exactly overhead at a point on the equatorial line. The subsolar point crosses the equator moving northward at the March equinox and southward at the September equinox.
The equinoxes, along with solstices, are directly related to the seasons of the year. In the northern hemisphere, the vernal equinox (March) conventionally marks the beginning of spring in most cultures and is considered the New Year in the Persian calendar or Iranian calendars as Nowruz (means new day), while the autumnal equinox (September) marks the beginning of autumn.