October Sky
We in the Northern Hemisphere experienced the autumnal equinox on September 22, with the hours of daylight and dark virtually equal.
Ever since, we have been turning away from the sun, the light growing softer and the shadows longer. There’s something about that fall light that creeps into our very being and says, “Slow down, take a break, catch your breath, and look around at this beautiful planet Earth.”
Poets and painters strive to capture the essence of that autumn lighting. “Autumn is a perfect season to be out painting en plein air,” says Jo Ridge Kelley, an award-winning contemporary painter from Waynesville, North Carolina. “With the sun at a lower angle in the sky, the light is sparkly and golden across the landscape.”
Kelley knows the soft autumn light won’t last long. “The colors on my palette are mixed a little warmer to try and capture this fleeting light,” she says. “I find I use more cadmium orange in my green mixtures and often tone the canvas with a wash of Indian yellow, creating a gold light that will bounce back through the other colors.”
There’s more than color theory behind this mysterious fall magic.
According to Brian Dennison, who earned his Ph.D. from Cornell University and teaches astronomy at the University of North Carolina-Asheville, the sun hangs lower in the autumn sky, when compared to the same time of day in the summer, because of the 23.5-degree tilt of the Earth’s axis.
“As we orbit the sun,” Dennison explains, “the Earth’s tilt does not change appreciably, but from a fixed latitude this causes the sun to appear high in the sky in summer and low in the winter. This occurs because the Northern Hemisphere tends to be oriented toward the sun in summer and away from the sun in winter.”
So as we are looking back over our shoulders at the autumn sun, the days are growing shorter. Dennison says this phenomenon occurs fastest in early fall. “We tend to easily notice the lowering sun and shortening days in late September and early October,” he says.
Dennison, who assisted in the development of the Lookout Observatory at UNC-Asheville, goes on to explain: “To many observers, the lower illumination angle of the sun may seem to cast a somewhat gentler appearance on the landscape, compared with the harsher illumination of the summer sun high in the sky. Perhaps most noticeably, shadows are longer in autumn. Also, when the sun is low in the sky, blue light tends to be scattered away by the atmosphere and the illumination reaching the ground has a somewhat greater proportion of colors at the opposite end of the spectrum, red in particular.”
In other words: Autumn is awash in the soft underbelly of the sun’s light; the warm reds and syrupy oranges are pouring out over the landscape. You may not know why, but your psyche is probably drawn to it. It’s the reason you slip on your sweater and go for a walk on those afternoons of Indian summer.
About the author: Don Hendershot is a naturalist in Waynesville, North Carolina.