AUSTIN (KXAN) – The fall equinox signals shorter days, falling leaves, pumpkin spice and cooler temperatures. However, what you may think you know about the equinox could be wrong.
First day of fall
The fall equinox does mark the beginning of fall, astronomically, but not meteorologically. Earth’s seasons are a result of two things: the rotation around the sun and the tilt of the planet. Because the Earth is titled at 23.5 degrees, not all the planet receives the sun’s rays equally. As the planet orbits the sun, the area of the planet that receives the most sunlight shifts.
The fall equinox marks the point in the orbit where the sun and Earth are perfectly aligned, and the balance of light is equal across the planet. It’s here where the warmer seasons shift to the colder ones.
Meteorologists mark the seasons by the months, with the three coldest months called winter and the three warmest called summer. The remaining six months of the year are called spring and fall. Because of this, you might hear the phrase “meteorological fall.” This is referring to September, October and November, the three transitional months from summer to winter.
A perfectly balanced day
The equinox is supposed to be the day of the year where you will see exactly twelve hours of day and twelve hours of dark, but this isn’t the case. You can blame the atmosphere for this one. Even though the Earth is aligned with the sun, the light doesn’t hit everyone the same. As the light breaches the atmosphere, it begins to refract. Because of this, the day is slightly longer depending on where you are. In Austin, the day is 12 hours and 8 minutes long.
Celebrations around the world
People around the world have many rituals to welcome fall. In England, people gather at daybreak at Stonehenge to welcome the equinox. In China, lanterns line the streets and pastries called mooncakes are eaten. The Lakota tribe in the Midwest celebrate by making and smoking a specialty tobacco.
The leaves change colors
A common misconception is that the leaves change color because it’s colder outside, but it’s the light that causes the change. Trees absorb light by producing chlorophyll. During the fall, trees slowly roll back production of chlorophyll to better conserve energy. It’s chlorophyll that makes trees green. Without it, the natural color of the leaves emerges, which are red, yellow and orange.
What’s the deal with pumpkin spice?
The “official” flavor of fall is pumpkin spice, but it hasn’t always been. According to the Washington Post, you can blame Trader Joe’s, not Starbucks, for popularizing the flavor when the company began selling pumpkin flavors during the fall in the 1990’s. The flavor is a blend of cinnamon, clove, ginger and occasionally pumpkin.