Chicagohenge is happening soon: What is it and when are peak viewing times?

Twice a year, Chicago's sunset and sunrise align perfectly with the city's east-west grid system, creating a spectacular view of the sun shining through the buildings.

Photo by horspowr1001/Flickr.com/CC BY-NC 2.0

(CHICAGO) Each year on the fall and spring equinoxes, photographers and skywatchers line the streets or stop their cars, to see a stunning view of the rising or setting sun outlined through the skyscrapers.

According to the Adler Planetarium, "It is almost that time of year when nature and architecture harmoniously come together to create the phenomenon known as Chicagohenge."

The city grid

Named after Stonehenge, the ancient site in England that was designed to align perfectly with the sun, Chicagohenge happens because Chicago is built on a nearly perfect east-west grid system.

What is unique in Chicago is that the phenomenon where the sunrise and sunset align perfectly with the grid system happens to fall on the spring and fall equinoxes.

When to see Chicagohenge?

Experts say the peak viewing times will fall between Wednesday, September 21st, and Friday, September 23rd.

However, the phenomenon has already begun. You can see the sun is starting to align with the buildings from this image captured by Barry Butler Photography and posted to Twitter of Monday's sunset.

What is the autumn equinox?

It's when the hours of daylight and darkness are almost equal. It occurs on September 22 at 8:04 PM and the sun will line up perfectly with the Chicago buildings. The Adler Planetarium reminds Chicagoans, "Do NOT look directly at the Sun when viewing this celestial alignment."

What's the best spot to see Chicagohenge?

As the Adler Planetarium says, "it's a no brainer!" Find an east-west facing street during sunrise or sunset, and enjoy the show.

What other cities have a similar phenomenon?

New York City, Toronto, and Montreal are also designed based on an east-west grid system. But Chicago is the only city where our 'henge' occurs on the spring and autumn equinoxes.

Tag the Adler Planetarium in your photos

If you're out there snapping gorgeous photos of the sun outlined through the buildings, be sure to share the phenomenal pics you capture on social media. The planetarium wants to see your Instagram photos of the event. Tag @adlerplanet and #Chicagohenge on Instagram or Twitter.

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