The bi-annual event occurs for the spring and fall equinox.
If your social media feeds haven’t already reminded you, Chicagohenge has begun in the Windy City. Chicago’s very own Stonehenge phenomenon, dubbed ‘Chicagohenge,’ is peaking this week between September 20 – 23. [Featured image: @_alexqian]
Of course you’re familiar with the prehistoric boulder formation in Wiltshire, England. Stonehenge is a worldwide tourist destination that attracts thousands of visitors every year. During the summer and winter solstice, the sun rises and behind the Heel Stone, where its rays are captured within the rock frame, creating a glorious spectacle.
For the second time this year, Chicago will have its very own Stonehenge spectacle. In the week running up to the fall equinox, which takes Tuesday, September 22 this year, the sun will align perfectly with Chicago’s east-west facing streets for both sunrise and sunset. The reason of the so-called Chicagohenge has to do with the equinoxes as well as Chicago’s grid system.
An equinox is one of the two times of the year (Spring Equinox and Autumn Equinox) that the Earth’s equator gets the most sunlight. It’s also the times of the year that Northern and Southern Hemispheres are distributed equal amounts of sunlight.
“Since the Earth’s axis is tilted, sunlight is not always distributed equally,” the Adler Planetarium writes on its website. “At any given point, one-half of the Earth is tilted towards the Sun more than the other. As the Earth orbits around the Sun, the part that was tilting away from the Sun begins to be the part that is facing towards the Sun.”
“During an equinox, the Sun rises and sets directly to the east and west.”
Because Chicago was built on a grid system, that is, with streets arranged at right angles into the shape of a grid — with streets lining up near perfectly on compass north to south and east to west — residents can witness the astrological phenomenon.
Between September 20 and September 23, park yourself on an east to west running street, and watch the spectacle radiate over the City of Chicago! Some favorite spotting locations include between Kinzie and Madison as well as E Randolph Street between N State St. and N Michigan Avenue. For the full Chicagohenge experience, you can capture the phenomenon along Washington Street from Millennium Park. On Monday, September 21, the sun rises at 6:37 am and sets at 6:48 pm. On Tuesday, it rises at 6:38 am and sets at 6:46 pm.