The first day of autumn or fall was Sept. 22 – last Wednesday. This date is also known as the autumnal equinox. So, what is an equinox? An equinox happens two times a year in the spring and in the fall. These are the only times when the sun’s center crosses the equator and day and night are of equal length everywhere!
The autumnal equinox marks the first day of fall in the northern hemisphere (north of or above the equator) and the first day of spring in the southern hemisphere (south of or below the equator). Isn’t it strange how it can be fall in on half of a country and spring in the other half! If you look at a map of the world you will see this. For example, in the upper half of The Democratic Republic of Congo it is fall and in the lower half it is spring.
The word “equinox” comes from Latin aequus, meaning “equal,” and nox, “night.” On the equinox, day and night are roughly equal in length. When the sun crosses the equator from north to south, this marks the autumnal equinox; when it crosses from south to north, this marks the vernal or spring equinox.
After the autumnal equinox, days become shorter than nights as the sun continues to rise later and nightfall arrives earlier. This ends with the December solstice, when days start to grow longer once again.
Did you know that the full moon that happens closest to the autumnal equinox is called the Harvest moon? That’s because of farming. Around the fall equinox, the full moon rises around sunset for several nights in a row, which traditionally provided farmers with just enough extra light for them to finish their harvests before the killing frosts of fall set in. Normally, the moon rises about an hour later each night, but around the time of the fall equinox, the angle of the moon’s orbit and the tilt of the earth line up just right and cause the moon to rise only about 20 to 30 minutes later each night for several nights in a row!
Another definition of fall is “nights of below-freezing temperatures combined with days of temperatures below 70 degrees Fahrenheit (21°C)”. From here on out, the temperatures begin to drop.
What are your local signs of fall? In many regions of the Northern Hemisphere, the landscape silently explodes with vibrant colors of red, yellow, and orange. The leaves begin to drop off the trees, providing endless hours of jumping into leaf piles for kids and raking them back up for parents!
Why do you suppose we call it fall? Could it be because all the leaves fall from the trees? What do you think?
The Old Farmer’s Almanac
Comments are not available on this story.
Send questions/comments to the editors.
