Spencer Finley

Business & Science Editor

sjf5814@psu.edu

The Autumnal Equinox occurred on September 22, 2021, marking the start of fall in the Northern Hemisphere. There are two equinoxes every year- the Vernal Equinox, which occurs in late March and marks the start of spring in the Northern Hemisphere, and the Autumnal Equinox, which occurs in late September and marks the beginning of fall in the Northern Hemisphere. 

According to Merriam-Webster, the term equinox is derived from a Middle English term equinocce, which is itself derived from the Latin term aequinoctium, which is a combination of the Latin terms aequus, meaning “equal,” and nox or noctis, meaning “night.” This is because the equinox is a day which is made up of equal parts day and night, with the day and night each lasting 12 hours. 

The equinox happens because the sun crosses the celestial equator in a southward direction; contrary to popular belief, the Earth’s seasons are not caused by the planet’s distance from the sun increasing or decreasing- in fact, the Earth is at its farthest from the sun in the middle of July. Rather, the seasons are caused because the Earth’s 23.5-degree tilt causes one side of the planet to receive less direct sunlight at a given time than another. 

While the Autumnal Equinox marks the start of fall in the Northern Hemisphere, the Autumnal Equinox marks the beginning of spring in the Southern Hemisphere, as areas South of the Equator experience seasons opposite those of areas North of the Equator. For example, while the Northern Hemisphere is experiencing winter, it is summertime in the Southern Hemisphere, and while the Northern Hemisphere is experiencing autumn, it is springtime in the Southern Hemisphere.