A unique, local phenomenon known as “Chicagohenge” has descended on the Windy City. Starting last Saturday and running through tomorrow, the sun perfectly aligns with Chicago’s east- and west-facing streets at sunrise and sunset.

Photo 127214251 © Kaili Wang | Dreamstime.com

During the Spring Equinox and the Autumn Equinox, Chicagohenge results in a yellow and orange glow illuminating buildings. Because of Chicago’s street grid system, the east-west streets provide a perfect frame at sunrise and sunset. The Chicagohenge effect can be seen from any street running east-west, but streets with tall buildings maximize the view.

The two equinoxes mark the beginning of spring and the end of summer. During the equinoxes, the Northern and Southern hemispheres experience equal amounts of day and night and the sun rises and sets directly to the east and west.

According to Chicago’s Adler Planetarium, the best times for viewing Chicagohenge are slightly before 7 a.m. and slightly after 7 p.m. Timing is everything, though, because these are the fastest sunsets of the year, lasting only a couple minutes.

— John Wroblewski, online writer