What the equinox ‘henge’ effect tells us about U.S. cities

The sun creates a "Chicagohenge" effect in Chicago, as the sun rises and falls straight down streets such as Kinzie and Madison one or two days each year, as seen here on Sept. 22, 2017.

The fall equinox, which arrives Tuesday in the U.S., brings shorter days, and chances to witness alignment between Earth and the sun. It’s a modern version of ancient observances of a celestial shift.

(Image credit: Bilgin S. Sasmaz)