Today is officially the first day of Fall, with Winter officially set to begin on December 21. Before it was called “Fall”, it was called “Autumn”, and before then it was called “Harvest”. While the modern names of winter and summer have been around for more than 1,000 years, the names of fall and spring are more recent—and less constant. Americans tend to use the word Fall while most of Europe prefers the word Autumn. Regardless of your preference, today is when the sun is directly in line with Earth’s celestial equator, or the equator projected onto the sky. Both day and night will last about equally as long today, with approximately 12 hours of daylight and 12 hours of darkness. This same phenomenon occurs on the spring equinox. Unlike spring though, the Northern hemisphere will begin receiving less direct sunlight due to the tilt of the Earth’s axis, bringing shorter and cooler days. With fewer hours of sunshine comes a change in leaf color as trees begin to go into hibernation, producing less green chlorophyll and allowing brilliant reds, oranges and yellows to peak through. The date of the fall equinox (and its spring counterpart) varies slightly each year, sometimes falling on the 22nd, 23rd, 24th, or 25th depending on the quirks of the calendar, along with Earth’s slightly irregular orbit. Below are some fun facts about the fall equinox.
Why Trees Lose Their Leaves – All deciduous trees will eventually shed their leaves as they head into dormancy for the winter. It’s a brilliant self-preservation technique, where the pathways that carry water to and from the leaves are “shut off.” This is due to the fact that if this soft vegetation contained water when harsh winter temperatures arrived, they would freeze and damage the leaf stems and then the limbs. In the end, the damage would eventually kill the tree. There is the exception though, with so-called “evergreen” trees. Evergreens do actually lose their “leaves”, but they do it in batches instead of all at once. Think of it like your own hair, which is continuously falling out and being replaced. Evergreen species also have a waxy coating which makes them resistant to the cold and keeps them from drying out. While the trees may look like they do even in warm weather, they are mostly dormant over the winter.
Changing Leaf Colors – With fewer hours of sunshine comes a change in leaf color as trees begin to go into hibernation, producing less chlorophyll. You may recall from your grade school science class that chlorophyll is the key component in a plants ability to turn sunlight into glucose, which in turn feeds the trees. Many millions of these chlorophyll cells saturate the leaves, ultimately making them appear green to the eye. However, when chlorophyll production slows down, the “true” color of the leaves are revealed, giving way to the brilliant reds, oranges and yellows of autumn foliage. Red and purple leaves are only that color because of the presence of sugars and sap that are trapped within the leaves. These sugars provide plants with the energy they need to survive. Evergreen trees such as pines, cedars, and spruces stay green because their leaves (needles) are covered with thick wax and they contain materials that prevent freezing when it gets cold. The U.S. National Parks Service actually has a state-by-state guide that outlines peak fall foliage, what the typical colors are and some of their recommended viewing spots.
Migrating Birds – Fall is a peak migration time for many species of birds. During autumn, birds will fly to other areas seeking more hospitable climates. The Arctic tern journeys about 11,000 miles each way for its annual migration. That is like going all the way across the United States about three and a half times!
Fall’s Full Moon – Autumn is preceded by the arrival of the Harvest Moon. Full moons are named for the month or season in which they rise and the Harvest Moon is the full moon closest to the autumn equinox, which occurred on the night of Sept. 16 this year. Before artificial lighting, farmers took advantage of the full moon’s light to harvest their crops. In late summer and early autumn, many crops ripen all at once, making lots of work for farmers who had to stay in the fields after sundown to harvest all the goods. This late season light, or the “Harvest Moon”, was essential to getting everything out of the fields.
Enjoy The Northern Lights – The aurora borealis, also known as the Northern Lights, tends to be visible this time of year. This is because geomagnetic storms are about twice as likely to occur during the fall thanks to cool evening weather.
Start The Diet Early – Weight gain around this time of year may not only be due to comforting fall foods like pumpkin pie and cider, but researchers have found the transition and dialing back of sunlight and “vitamin D” could reduce fat breakdown and triggers increased fat storage. Kinda of like when a bear’s body prepares for hibernation during the winter months. Perhaps our bodies are wired to store more food as we head into the winter months?
