Aspen trees during fall, Fishlake National Forest, Utah

Midway to winter. Autumn equinox

Fall isn't just marked by the calendar. Each September, Earth's subtle tilt brings the autumn equinox—one of two times a year when day and night are nearly equal in length. It marks the beginning of fall in the Northern Hemisphere. From solar alignments to changing leaves, nature offers its own quiet signals that the season has shifted. While for most of us it may seem like just another day, ancient cultures paid close attention to this change. Sites like Chichén Itzá in Mexico and England's Stonehenge were designed to align with the rising or setting sun during equinox days.

One of the best places to catch the change in season? Fishlake National Forest in Utah. As September rolls in, the aspen trees seen in today's image begin their annual transformation, turning vivid shades of yellow that ripple across the hills. The forest covers more than 2,300 square miles of lakes, trails, and mountains that shine with fall color. There's something grounding about watching the season change in sync with something much older than the Gregorian calendar we follow.