Spring Equinox Arrives, Allowing For 'Chicagohenge' Phenomenon

CHICAGO — As Chicago residents have eagerly been awaiting spring, the calendar made it official on Monday, coinciding with a twice-a-year city phenomenon that has local residents and visitors alike reaching for their cell phone cameras.

“Chicagohenge” arrives on Monday, kicking off a three-day period when both the sunrise and sunset align perfectly with the city’s grid system. Astronomical spring arrives at 4:24 p.m. on Monday, when the spring equinox begins in a much-anticipated changing of the seasons.

According to Adler Planetarium, the occasion is one of two times a year when the sun directly lines up with Chicago’s east-west facing streets. A blog on the planetarium’s website states that Chicago’s streets line up almost perfectly with the cardinal east and west directions on a compass.

“This in turn sets up the perfect stage for Chicagohenge to take place,” the blog reads.

There are two times a year when the Earth’s equator moves most of the sunlight. When this happens, the planetarium says, the planet’s Northern and Southern hemispheres experience equal amounts of day and night.

The sun rises and sets directly to the east and west during an equinox. Meteorological spring began on March 1.

The sunset on Monday is anticipated at 7:02 p.m., setting the stage for "Chicagohenge", which will be visible between March 20 and 23. The best views will be available just before sunset and right after sunrise, according to the planetarium. Sunrise took place at 6:54 a.m.

Among the most popular spots to view the phenomenon on intersections between Kinzie Street and Madison Street, although looking down any east-west street in the downtown area should provide a good view.