The fall equinox brings shorter days and marks the transition of seasons. In several U.S. cities, this time also offers an opportunity to observe a unique alignment between the sun and urban landscapes. As the sun rises and sets, it aligns with streets running east and west, creating a striking visual effect. This phenomenon is reminiscent of ancient celestial observances such as those at Stonehenge.
In Chicago, this alignment is known as “Chicagohenge.” Geoff Boeing, Chair of the Department of Urban Planning and Spatial Analysis at the University of Southern California, highlights how city design influences our interaction with the universe. Michelle Nichols, Senior Director of Public Programs at the Adler Planetarium in Chicago, notes that the city’s architecture enhances this effect, with tall buildings framing the sun during sunrise and sunset.
Chicago’s street layout follows the cardinal directions, a factor that contributes to the occurrence of Chicagohenge. Wide streets running east and west provide ideal conditions to observe this phenomenon. The fall equinox of 2026 will arrive on September 22, with nearly equal hours of day and night.
Other cities like Washington, D.C., and Phoenix with grid layouts also experience similar “henge” moments. Historically, many cities were designed to reflect celestial arrangements. Ancient cities often served religious and spiritual purposes, aligning their urban plans with stars and celestial events.
Modern urban alignments with celestial features are usually unintentional outcomes of city grid designs. These alignments still hold significance for residents, photographers, and tourists. They are reminders of the sky’s ever-present influence.
Cities with street grids aligned with the compass, such as Chicago and Denver, offer excellent opportunities for equinox viewing. Geoff Boeing’s analysis shows these cities exemplify 19th-century urban planning styles that spread across the Midwest during the Great Westward expansion.
Some cities, like Manhattan and San Francisco, deviate from compass alignments due to geographical features. Despite these variations, unique celestial alignments may still be observed in such places.
With technological advancements, events like the equinox have gained popularity on social media due to their photogenic appeal. Michelle Nichols advises safety for those seeking to capture these moments. She warns against capturing photos from the middle of the street and reminds drivers of potential sun glare on east-west streets during morning and afternoon commutes.