This year, the last day of summer is Sept. 22. GETTY IMAGES

Labor Day marks the ceremonial end of summer, but there are still a good few weeks to enjoy the season, even after the three-day weekend ends and schools begin their calendar year. This year, the last day of summer is officially on Sept. 22. The fall equinox arrives Sept. 23 and so does the onset of shorter days in the Northern Hemisphere.

Equinox is derived from the Latin words aequus, which means equal, and nox, the word for night. The equinox occurs twice a year -- spring and fall -- when both the northern and southern hemispheres receive equal rays of sunlight. There are also two solstices that signal the change of seasons in the summer and the winter.

At the equinox, daytime and nighttime extend about the same length of time and the sun appears directly overhead at noon. Nights become longer after the fall equinox as the Earth orbits around the sun on its tilted axis.

According to Mental Floss:

In pagan mythology, the equinox is called Mabon, or Second Harvest. It is a time to give thanks for the summer and to pay tribute to the coming darkness. It is also a time of preparing for Samhain (October 31–November 1), the bigger pagan festival that begins winter. SomeWiccan rituals for Mabon include building an altar with harvest fruits and vegetables, meditating on balance, gathering and feasting on apples, offering apples to the goddess, sharing food, and counting one’s blessings.

The day is the perfect opportunity to find "due east" and "due west," so those who find themselves in the Northern Hemisphere that day can take the opportunity to find a scenic sport and watch the sun rise and set.

Want to know more about the change of seasons? Check out this video below in which Dr. Laura Danly explains the equinox at the Griffith Observatory in Los Angeles.