Chicago....it's my kind of town – except with its light pollution! According to National Geographic Magazine, Chicago has held the dubious title of most light polluted city in the U.S. since 2008.
Light pollution effects us in many obvious and not so obvious ways. The stars you see over downtown Chicago now number only in the dozens on the clearest nights, compared to the many thousands you see on a clear moonless night in the least light polluted areas of the country (Figure 1).
The cost of electricity to light up the sky (rather than where it is needed) is estimated to be over $2.2 billion in the U.S. alone.
In fact, recently someone called me thrilled to see a lone bright “star” from their apartment on the west side. It was actually brilliant Jupiter, the only star-like object they have ever seen from their apartment.
Here at the Adler, we have the best view of the city skyline, so the best view of the sky is over the lake. A time exposure photograph of the spiral galaxy M81 (Figure 2) using our lakefront Doane Observatory’s 20-inch (0.5-meter) telescope shows the effects of changing light pollution across a small region of the sky.
Fortunately, Adler Astronomer Emeritus, Jim Seevers was consulted about the parking lot lighting around the museum campus, so most of those light fixtures are “full cut-off," allowing no light to spill up into the sky. However, many other lights along the lakefront and the acorn-shaped light fixtures on the museum campus create sky glow.
Recent medical studies confirm that light pollution produces additional risks of cancer, depression, and obesity. Animals and insects also see the effect of light pollution and their reactions may be even scarier. Anyone who has viewed the myriad insects circling a light pole on a warm summer night sees that insects are confused by light pollution. Some of those insects are night pollinators and without them, prices and availability of fruits, vegetables, and grains could change dramatically.
If we join together to keep lights focused where we need them, perhaps some day our children or grandchildren will see the faint glow of the Milky Way even from downtown Chicago (Figure 3).
Larry Ciupik is an Astronomer and Director of the Doane Observatory at the Adler Planetarium.