Into the Darkness with the Autumn Equinox
Into the Darkness with the Autumn Equinox
Written by Kristine Manganelli (Somerset County 4-H Coordinator)
If they haven’t left yet, monarch butterflies and migratory birds like hummingbirds, are making their way South to overwintering grounds. The decreasing daylight hours signals that it is time to go, and sets in motion many processes in nature.
Ever since the Summer Solstice in June (the longest day of the year), we have slowly been losing the amount of light we experience each day. On Tuesday, September 22 the Autumnal Equinox will take place for us here in the Northern hemisphere. The equinox marks the turning point when darkness begins to exceed the amount of daylight.
At exactly 9:31 am (EST) the sun will be directly above the equator. At this moment the solar terminator, or dividing line that separates day and night (also referred to as the Twilight Zone), passes directly through the North and South poles to give us equal parts day and night.
In fact, the word equinox comes from the Latin words ‘aequus’, meaning equal, and ‘nox’, meaning night. Earth is equally bathed in daylight and darkness twice a year; in September for the Autumnal Equinox and in March for the Vernal Equinox, which marks the transition to Spring.
Solar Terminator from Space
After the Autumnal Equinox, the daylight hours will continue to shorten until the shortest day of the year on the Winter Solstice in December. From here, daylight will increase until it is equal again with night at the Vernal Equinox, and until the longest day on the Summer Solstice in June where the cycle begins again.
As Earth orbits around the sun, it is tilted on its axis at a 23.5 degree angle. The summer and winter seasons are determined by whether the hemispheres are tilted closer or farther from the sun. When the Northern Hemisphere is tilted towards the sun, the sunlight is direct, causing the hotter days of summer.
At the same time the Southern Hemisphere is tilted away from the sun, causing indirect light and the cool temperatures of winter. However, during the Vernal and Autumnal Equinox, Earth has no tilt, so the terminator line is parallel to the Earth’s axis and lines of longitude.
Even though the darkness of autumn can be daunting, the Equinox is also associated with Harvest season, when summer’s crops are ripe and thriving. At this time of year, farmers are busy harvesting the remaining crops before the first frost.
The abundant crops are frozen or preserved into pickles and jams to last through winter, just as the squirrels collect and store away nuts. Now is the time to enjoy your favorite summer vegetables like tomatoes and cucumbers while they are still fresh.
Harvest season allows us to be grateful for summer’s fruits, and prepare for the period ahead when the lack of sunshine and warmth make the land inhospitable to growth. Take comfort in knowing that the darkness is not permanent, and as Earth continues its journey around the sun, we will come out on the other side.
Get Outside
Celebrate the Autumnal Equinox and enjoy the last days of warm weather by watching a sunset with your loved ones. Add a picnic featuring summer’s bounty to acknowledge Harvest Season as well.
Try out the Sunrise & Sunset Calculator from The Old Farmer’s Almanac to find out the perfect time to watch, as well as to calculate the hours of daylight in your area on the Equinox and throughout the year.
Sources:
“Autumnal Equinox 2020: The First Day of Fall.” 18 Sept. 2020, The Old Farmer’s Almanac, https://www.almanac.com/content/first-day-fall-autumnal-equinox. Accessed 18 Sept. 2020.
Becker, Rachel A. “Fall Equinox 2019: What it means, and why it matters.” 23 Sept. 2019, National Geographic, https://www.nationalgeographic.com/news/2015/09/150922-equinox-autumn-seasons-sun-moon-space-science/. Accessed 18 Sept. 2020.
“Fall Equinox – When Is the First Day of Fall?” Farmer’s Almanac, https://www.farmersalmanac.com/fall-equinox-first-day-of-fall. Accessed 18 Sept. 2020.
“What and when is the autumnal equinox?” Royal Museums Greenwich, https://www.rmg.co.uk/discover/explore/what-autumnal-equinox-when-it-and-what-are-dates. Accessed 18 Sept. 2020.