There are two days each year when day and night are the same length. One is in March and the other in September. These days are called equinoxes. (E-qui-nox-es. Sort of rhymes with see the foxes.)

Equinoxes are the same in the upper half of the earth and the lower half (called hemispheres.) So days when daylight and darkness are the same  happen where we live as well as where people far down in South America live.

To understand equinoxes and why they happen, picture a basketball spinning on someone’s finger. The basketball is not leaning to one side or the other, it is straight up and down. The point at the very top of the spin is directly over the person’s finger.

The Earth spins like a basketball, but it is not straight up and down. It is leaning over about one quarter of the way. If a basketball leaned like that, it would fall off the finger! The Earth, of course, doesn’t fall off anything, it just spins at that odd angle.

Because of this, during part of the year the northern area of the Earth is leaning toward the sun and the bottom part is leaning away.

But when the Earth travels half-way around the sun, the northern part is then leaning away and gets less direct sunlight, and the southern part is tilted up and gets more sun.

That’s why when it’s summer for us here, it’s winter for people in South America, Australia, and other places far south. And when it’s winter here (because we are tilted away from the sun, so getting less direct sunlight), it’s  summer in those places (because they are tilted up and get more direct sunlight.)

If you can’t picture this, don’t worry. You will study it in a science class and there will be pictures and videos to make it clear. For now, though, just know that in March, there is a day of equal day and night, and in September, there is another day of equal day and night.

For us, the equinox in March is called the spring or vernal equinox. The one in September is called the fall or autumnal equinox (aw-TUM-nal). The one in March marks the beginning of spring and the one in September marks the beginning of fall or autumn.

Because of leap years and some other factors, the exact dates and times of the two equinoxes may vary a little bit. This year the spring equinox was on March 20 and the fall equinox will be on September 23.

Enough of all that. Let’s now get to the fun part.

Because the autumnal equinox marks the beginning of fall, there are many special activities that take place around that day.

People like to take nature walks. The trees are changing colors, their leaves turning from green to beautiful shades of gold, red, and yellow. It’s fun to collect some of the fall leaves and use them in craft projects or to learn which kinds of trees they fell from.

Some people even decorate their rooms (or classrooms) with the colorful leaves.

Because fall is a time when vegetables and fruits become ripe, people pick fresh veggies and apples or buy them from farm stands.

The evenings are getting cooler, so many people like to build campfires, cook their favorite camping foods, and sing songs or tell stories.

Different countries and cultures have traditions connected with fall. For many, harvest is a time of great celebrations and thankfulness.

There are a number of children’s books about fall, such as Fall Leaves: Colorful and Crunchy by Martha E. H. Rustad; Goodbye Summer, Hello Autumn by Kenard Pak; and We Gather Together: Celebrating the Harvest Season by Wendy Pfeffer.

Fun Facts

•  The word equinox comes from the Latin words aequi, which means equal, and nox, which means night. As you might guess, our word equal comes from aequi.

•  Saturn also leans and has equinoxes. But they happen only every 14.7 Earth years. Its last one was on August 11, 2009, and the next one will be May 6, 2025.

•  The full moon that happens closest to the fall equinox is often called the harvest moon. There’s even an old song that goes, “Shine on, shine on harvest moon up in the sky . . .”

•  There are two days each year when there is either the longest daylight of the year (at the beginning of summer) or the shortest daylight (at the beginning of winter.) These are called solstices. (SOHL-stih-ses. Sort of rhymes with holes with fizz.) These happen in June and December.

•  Though we capitalize the days of the week and the months of the year, we do not usually capitalize the seasons summer, fall, winter, and spring.