On Wednesday, September 23rd at 4:21 pm EST, the sun will reside directly above the Earth’s equator, signaling the end of the summer season and the official beginning of the fall equinox for the northern hemisphere. More formally referred to as the Autumnal Equinox, this is one of two dates within a calender year during which the daytime and nighttime hours along all latitudes approximately equate with one another. The other instance occurs during the spring equinox, also called the Vernal Equinox, which generally takes place around March 21st.
The etymological origin of the name “equinox” stems from the Latin root words “aequus” and “nox”, roughly translating to mean “equal” and “night”, respectively. Dating back to at least the first century BCE, observing the yearly astrological event of each equinox has informed calender formatting, while also becoming celebrated bi-annual occasions, across countless cultures and societies.
As it rotates on a tilted axis, the Earth’s hemispheres receive varying amounts of light and heat depending on their location relative to the sun. This natural phenomena is reflected in the world’s regionally distinct seasonal weather patterns. Along with the two solstices, which indicate either the furthest or the closet hemispheric distance relative to the sun, the equinox present a unique moment in astrological location.
During the equinox, the Earth’s axis tilts neither toward nor away from the sun as it does at all other times, providing roughly the same amount of sunlight hours to both the northern and southern hemispheres. Once the equinox has passed, one hemisphere will begin experiencing more sunlight hours and the other will begin experiencing less. As such, the seasons of the northern and southern hemispheres transpire in an inverse relationship: while summer or spring occur on one side of the equator, winter or fall take place on the other.
Because the Earth’s axis resides at a 23.5 degree angle, the seasonal changes in sunrise and sunset do not occur at exactly even rates. The Earth’s movement in an elliptical rather than circular movement around the sun further compounds this slight difference. The sun moves at an incrementally more rapid pace about the earth than practically rounded human time would indicate. For this reason, after the fall equinox, the sun noticeably appears to set earlier in the evenings, while the earlier sunrises might seem to occur less remarkably. With lengthening nights comes colder weather, although September and early October can feel mild or moderate in temperate climates.
Culturally, the spring equinox inspires rebirth while the fall equinox evokes conservation. Autumn is the season during which humans and all other life prepare for the hardships of the winter months by shedding excess and accumulating base necessities. Crops are planted near the spring equinox and harvested around the fall equinox. Common tropes of the each equinox are artistically expressed through the representations of the budding first plant in spring or the changing leaves of autumn. Each event arrives with it’s own distinct beauty typified by particular natural transformations.