Friday, Sept. 22 marks the beginning of fall in the U.S. on the autumnal equinox at 4:02 pm EDT in the Northern Hemisphere. The equinox is defined as when day and night are the same length, approximately 12 hours each. The month also brings with it the harvest season. 

Here are some facts and trivia about the season of cardigans and pumpkin juice. 

1. The terms "fall" and "autumn" are used interchangeably, with the latter being more popular among British people.

2. Those who live closest to the equator, which is the center of the planet, never experience the season of autumn. 

3. According to, before the 1600s, the term "harvest" was used to describe fall, as farmers would reap what they had sowed in the spring and prepare for the coming winter. As time went by, poets coined the phrase "the fall of leaves" — shortened to "fall" in the 1600s.

4. NASA says that the chance of seeing the stunning aurora borealis or "northern lights" increases after the fall equinox. This is said to be because fall produces a surplus of geomagnetic storms.

5. Although leaves have the potential to be yellow and orange throughout the year, the colors are not often seen during other seasons. This is because while the pigment chlorophyll gives leaves their green color during spring and summer, decreased daylight and cooler temperatures at the end of these seasons cause chlorophyll to break down which exposes other pigments that cause the brilliant yellow, orange, red leaves of fall. The changing leaves are called "koyo" in Japanese.

6. Many festivals and traditions celebrate the arrival of autumn, from the Jewish Sukkot to the Chinese Mid-Autumn Festival. In the U.S., Halloween is also celebrated during fall.

7.  For modern Pagans, the two most important of holidays that celebrate harvest and death — which are associated with the equinox — are known as Mabon and Samhain.

8. Chinese and Vietnamese communities all over the world celebrate the Moon Festival, on the day of the Harvest Moon, which is the full moon closest to the equinox.

9. Average fall temperatures in the United States can range from about 21.1 degrees Celsius to about -1.1 degrees Celsius, depending on which state you live in. The warmest state in fall is Florida and the coldest is Alaska.

10. Fall birthstones include sapphire (September), opal and tourmaline (October), and yellow topaz and citrine (November).

11. Studies have said that libido and testosterone are highest during the fall. It is speculated that this is triggered by decreasing daylight or increased social activity.

12. A long-standing myth of the equinox is that it's possible for an egg to stand on its end on the day. “The origins of this myth are attributed to stories that the ancient Chinese would create displays of eggs standing on end during the first day of spring," John Millis, assistant professor of physics and astronomy at Anderson University stated in an article.

13. During the season, many species of birds migrate to other parts of the globe. This is done to in order to seek for more hospitable climates.