Seeing Stars: Light Pollution’s Impact on Our Views of the Cosmos
October 4, 2024Written by: Matthew Buie
As the days grow shorter and the crispness of autumn fills the air, now is the perfect time to bundle up and gaze upward into the cosmos. But did you know that the sparkling stars we dream of are often hiding behind a veil of artificial light? Today, QMNH volunteer and aspiring astrophysicist Matthew Buie is exploring a phenomenon that might not be on your radar: light pollution. This silent intruder washes away the magic of the night sky and dims our connection to the universe above. If you’ve ever marveled at the beauty of a starlit night or longed to see the Milky Way in all its glory, read on to discover how you can help reclaim the wonder of the dark.
Have you ever looked into the night sky and been amazed at the immensity of the universe? How many stars could you see? Was it the “billions and billions” that Carl Sagan promised? Was it the “Million Stars” that campgrounds advertise? What if I told you that the average person can only see 6,500 stars worldwide?
Oh, and an important note – that’s how many stars in a very dark sky.
But what IS a “very dark sky?”
Children, in their blissful naiveté, will happily scribble a page in a thick layer of black wax to indicate a night sky. More experienced artists might use a midnight blue, grey, or even sepia pencil crayon to reflect a more accurate sky – filled with a handful of stars, perhaps a planet or moon, smog, wildfire smoke, various other obscuring phenomena, and light pollution.
When we think about pollution, our minds link to words like trash, oil spills, smoke, haze, smog, and possibly even the noise of the freeways, airports, construction zones, and seaports. But far down on the list of pollutants, much farther down than most people look, is light pollution. Light pollution turns the black blanket of night into a grey, yellow-brown, or even nearly sliver-white sky. It hides all but the brightest stars and planets, and can even hide the achingly beautiful Aurora Borealis from us.
There exists a scale to measure the amount of light pollution in an area. Named after amateur astronomer, John E. Bortle in 2001, it is a scale from 1 to 9, with the scale increasing with the level of light pollution observed. The specific levels are determined by whether or not you can see certain deep-sky objects with the naked eye, and they correspond roughly to specific densities of human habitation.
A scale 9 sky, for example, equates to an “Inner City Sky,” which you can easily see on a Dark Sky Map in places like Hamilton, downtown Toronto, Pearson Airport, Scarborough, and most of Montreal, isolates us from almost all the features of the night sky. There are essentially no constellations, no deep-sky objects except for the Pleiades (aka the Seven Sisters), and almost certainly no aurora. Here in Trenton, we can expect a sky between 6 and 7, where the Andromeda galaxy may or may not be seen as an indistinct haze.
Travelling out toward Sandbanks Provincial Park, you’ll be able to experience a sky closer to a 4, and going up to see our friends at the Lennox and Addington Dark Sky Park will start to show you the true and awesome depths of the universe, with a sky approaching a 2 on this scale. And finally, a trip into the depths of Algonquin Provincial Park will show you galaxies, ancient supernovae, newly born stars, only a few dozen thousand years old, and if you pay close attention, you may even be able to see faint shadows cast on our home planet by the light reflecting off Jupiter, Mars, or even originating from other stars!
This light pollution is more nefarious than just obscuring the night sky from us though. Many studies have shown that light pollution disrupts the sleeping patterns of all creatures, causing low but constant levels of stress that lead to susceptibility to disease, chronic exhaustion, and even increased risk of premature death. And while you’re now concerned for the animals who are affected by this, remember that we humans are included in this group too.
What can we do to help reduce the effect of light pollution? Start with your own home! Turn lights off when they’re not needed, both indoors and outdoors. Shutter your outdoor lights so they don’t shine farther than the other side of the street. Change over to lights toward the “warm” end of the spectrum, that don’t have the power to shine far into the night. And while you’re at it, LED lights use less energy for the same amount of light, which helps in other ways. Bring the topic of light pollution up to your city councillors, and see if there’s anything that can be done about it.
But above all else, do yourself a favour. Take some time to get out of the “light dome” of your city, and look into the night sky.
