Who Turned On the Lights??

I’m a space nerd (shocker, I know) so it’s probably not that much of a surprise to find out that I think light pollution is A Bad Thing. Light pollution, as defined by the National Park Service, is “excess or inappropriate artificial light outdoors”. It’s when our houselights and streetlights and headlights and all our other kinds of light spill upwards into the night sky.

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For an astronomy fan, the big issue with this is that all that excess light in the sky makes it harder to see the stars, the Milky Way, and anything that isn’t exceptionally bright on its own (looking at you, Moon!). But there are all kinds of effects from light pollution that have nothing to do with astronomy, including impacts on human health, environmental health, and cultural health.

Fortunately light pollution is a reversible process with the right efforts, and on Thursday September 25^th there is a hearing in the Massachusetts State House on Bill H.3493/S.2243, “An Act to improve outdoor lighting, conserve energy, and increase dark sky visibility”, also known as the “Dark Sky” bill, which hopes to require future lighting installations in the state to reduce light pollution. Turns out we’re the only state in the US Northeast that doesn’t have a law like this already! So in honor of this upcoming hearing I thought it would be a good idea to look at all the ways light pollution can mess things up (it’s a surprisingly long list) and what bills like H.3493/S.2243 can do about it.

Bright Eyes

We’ll start with what might be the most practical implications of light pollution for the average person on the street, someone for whom appreciating a dark sky is not a matter of personal importance (not me, in other words). Light pollution is still capable of wrecking that person’s day.

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Humans evolved under a clear day-night cycle, with a very bright part of our day and a very dark part. Our whole biology developed using that as one of its principles. The darkening at the end of the day is a trigger for certain biological and chemical processes in our bodies triggering, for example, the onset of an effective sleep period. This is known as our circadian rhythms.

But now the dark part of the day isn’t so dark. We have light leaking into our lives constantly. Odds are that unless you live way out in the middle of nowhere, there is light from buildings or street lamps or event from within your own home making its way into your bedroom at night. That can mess with your sleep cycle and that, my friends, can cause a whole cascade of other problems.

Disorderly sleeping has been linked to a raft of physical and mental health challenges, such as weight gain, anxiety, depression, and diabetes. That’s aside from the obvious effect that people who aren’t getting enough good sleep are more likely to get into accidents or have difficulties with coordination. Not all sleep disorders are caused by light pollution, obviously, but all that extra light telling your biology that it must not actually be time to go to sleep yet isn’t going to help anything.

But there are less obvious links between human health and light pollution that are still being uncovered. Studies within the last few years have linked light pollution to issues as widely varied as Alzheimer's, breast cancer, macular degeneration, and childhood thyroid cancer, among many other things. It’s becoming more and more apparent that when bodily rhythms get disrupted as badly as they can by excess lights at night, it can seriously screw up the whole system.

Think of the Birds!

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So light pollution is bad for human health. Extrapolate that out and you can probably guess it is doing the larger environment exactly zero favors as well. Plants and animals, after all, evolved with that same day-night cycle that humans did, and disrupting it with extra light at night messes with all sorts of things in the natural world.

What do mountain lions, toxic algae, zebrafish, and honeybees have in common? They are all carbon-based lifeforms, yes, but also they are all really negatively affected by light pollution. Well, not the toxic algae. Actually the toxic algae loves the light pollution—a study theorized that it’s helping fuel blooms of harmful cyanobacteria, so really it’s everybody around the toxic algae that’s negatively affected in that case.

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But light pollution is also causing anxiety in zebrafish, who are even passing on their internalized trauma to the next generation (inter-generational zebrafish trauma is not something I thought I’d ever be writing about on a space blog, but here we are. Thanks light pollution!). Studies also show that fish are drawn to light polluted coastlines at night, where they become smorgasbords for predators. All that extra light seems to be screwing up mountain lions’ abilities to hunt at night, it’s leading to a drastic decline in moth numbers, and it’s causing the same sort of sleep disorders we see in humans in honeybees. And then there’s what it’s doing to the birds!

I was unaware, before I started learning more about the effects of light pollution, how much birds move around at night. A lot of species migrate in the darker hours (as many as 70% of migrating species!), and a lot of them use celestial navigation to do it. That’s right, birds can navigate by the stars (as can other species, it turns out). And even birds that don’t use the night sky as a compass will often still use lighting cues to orient themselves. So you can imagine what happens when we blast the night sky with extra light. Spoiler: it’s bad.

Light pollution draws migrating birds in greater numbers into urban areas. There they may suffer from all sorts of issues, such as the inability to find the food they need, increased predation, or inability to orient themselves and actually get where they need to go to, you know, survive. And that’s if the buildings don’t get them first. A study from last year estimated that bird strikes against the window of lit buildings may be responsible for over one billion bird deaths each year. Over one billion. That is a lot of dead birds.

Bye, Bye Sky

Aside from health and environmental issues, the loss of the night sky has obviously implications for astronomical science (and it’s encroaching even on our darkest observatory sites) and for anyone who likes to look at the night sky. Living in the Boston area it’s a pinch I feel every night. Want to see the Milky Way? Forget it. A comet passing by? Don’t bother. Solar storm sparking a spectacular aurora display? No way. Heck, want to see anything except the dozen brightest stars in the sky? Good luck.

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Obviously for someone who likes to watch the sky, that’s a personal misfortune. But it’s an even greater tragedy than it seems, because for most of human history we have been deeply and dearly connected to the night sky.

Some of our earliest surviving architecture was built in alignment with celestial events, like the rising of Venus or sunrise on the solstice. Before compasses were invented it was the stars we used to navigate, allowing explorers to cross continents and oceans using the sky as a map. We calculated our calendars based on the regular motions of the stars, planning our festivals and scheduling plantings and harvests around the rising and setting of specific objects. And, of course, it was our storybook.

Cultures across the world made up stories that they wove and painted across the stars, some of which survive today as our constellations. It’s even theorized that a star story may be the oldest surviving human tale, something that is so old that it doesn’t belong to any one individual culture but to all of us. Humanity’s personal connection to the night sky is something that has been passed down for millennia.

But not anymore. That long line of links back to our earliest ancestors is being broken because we’re losing our sky to light pollution. Skyglow from light pollution increases at roughly 10% per year worldwide and around 75% of Massachusetts residents can’t see the Milky Way from where they live. That cultural history is something that belongs to all of us, and we are losing it.

The Solution

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Here’s the good news: unlike basically all other forms of pollution, light pollution can be fully and easily reversed. All we have to do is change the lights we use and how we use them. And it makes sense! Not only is the long list of negative effects from light pollution on everything from humans to zebrafish growing longer and longer, but light spilled into the sky is wasted energy and light fixtures that don’t spill light upwards use less energy (and therefore cost less) and focus that light where it’s actually needed (on the ground). Installing these more efficient lighting system just makes sense.

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That’s the focus of the hearing this Thursday at the Massachusetts State House. The Dark Sky bill won’t reverse light pollution in the state, but if passed, it will require the state to start using more efficient light fixtures going forward. If you happen to be a resident of Massachusetts and would like to support the bill, you can watch the hearing live or submit written testimony through 5pm on October 2^nd. You can also find ways to support the bill on the Museum of Science’s Take Action web page.

And if you don’t live in Massachusetts, that doesn’t mean you can’t do something! This is an issue that affects everyone, everywhere. Look for activist groups in your area or start a campaign of your own. After all, that’s your night sky that’s being lost. It’s time we fight to get it back.