Saving the Night — A Brief Look at Light Pollution (Reduction)

By:  Kayleen Glaser

Several years ago, I took a backpacking trip to Big Bend National Park in Far West Texas.  The first day I arrived, I was enchanted by the desert… it was seemingly endless, the red and oranges hues of the dirt fascinated me, it was flat for miles, and then huge mountains jutted out of the ground in the distance.  But my days spent in Big Bend were nothing compared to my nights.  “Why?” you may ask.  Because the Big Bend night sky has the least amount of light pollution in the lower 48 states.  On a clear night, viewers can observe, with the naked eye, some 2,000 stars.

When I returned to Bloomington after that trip, I started wondering what we could do in urban settings to make our night skies more vibrant, awe-inducing experiences.  The answer, in some ways, is quite simple:  light pollution reduction measures.  

First things first, what is light pollution?  Light pollution is “artificial light that shines where it is neither wanted, nor needed.”  Light pollution increases the illumination of our night sky and it includes effects such as sky-glow, light trespass, and glare.  Sadly, about two-thirds of the United States population has lost the ability to see the Milky Way with the naked eye at night due to light pollution.  The picture below illustrates the disparities in individuals’ ability to view stars in the night sky because of light pollution.


So what? Why care about reducing light pollution?  Well, beyond a love of the night sky, light pollution reduction increases energy efficiency and saves money in utility costs.  Interestingly, reducing light pollution could prevent disruption to organisms’ circadian rhythms — in humans, our circadian rhythm is our internal clock which tells us when to sleep (to put it simply).  Less disruption of this rhythm is linked to less depression, insomnia, cardiovascular disease, and cancer.   Further, less light pollution is more friendly to the plants and animals that share this world with us.

Methods to reduce light pollution are relatively easy:

  • Fully shield light fixtures to make sure that no light escapes to places where it is not wanted or needed (see below)
  • Eliminate over lighting
  • Shut off lights when not in use
  • Make better fixture choices


WAIT A MINUTE?! Doesn’t reducing light pollution decrease our safety??  Contrary to this seemingly intuitive argument, light pollution reduction measures can actually help increase safety at night by reducing glare on our eyes.  Bad lighting (i.e., lighting that shines directly into our eyes instead of at the ground) destroys our eyes’ ability to build night vision; further, it causes our pupils to constrict and let in less light.  Last, bad lighting increases the contrast between lit spaces and dark spaces and prevents us from seeing into the shadows.  The pictures below illustrate this effect:

In the first photo, glare lighting is being used:


In the second photo, the light has been shielded (note that this is the SAME picture):


All things considered, reducing light pollution has many benefits: from saving on energy costs to increasing night time vision to simply seeing more stars in the night sky.  Addressing light pollution on IU’s Bloomington campus has many benefits for the university.

  • First, eliminating some sources of light pollution will reduce energy usage, thus reducing utility costs and carbon emissions (as in accordance with the Master Plan).  Reduced light usage within buildings will also help reduce heat given off within buildings and slightly reduce cooling costs. 
  • Second, eliminating sources of light pollution will improve students’ quality of life by eliminating some glare that shines into dorm rooms during sleeping hours and will allow students the opportunity to see the stars at night. 
  • Third, light pollution reduction measures will help major, new and renovated buildings achieve LEED silver certification. 
  • Fourth, light pollution reduction measures will have a positive impact on the Campus Observatory and the astronomy department.  

Let’s start planning better and working toward a more brilliant night sky!


 “Controlling Light Pollution.” Light Pollution. International Astronomical Union, n.d. Web. 22 Nov. 2013. <;.

Chepesiuk, Ron. “Missing the Dark: Health Effects of Light Pollution.” National Center for Biotechnology Information. U.S. National Library of Medicine, 29 June 0005. Web. 27 Dec. 2013. <;.

(Photo credit) Diaz, Jesus. “Why Living In Cities Sucks.” Gizmodo. Gozmodo, 8 Oct. 2010. Web. 22 Nov. 2013. <;.

(Photo credit)


2 thoughts on “Saving the Night — A Brief Look at Light Pollution (Reduction)

  1. Thank you for the great article on light pollution! Another great resource is the International Dark-Sky Association, an nonprofit that has been working for the past 25 years to save the night skies. The IDA website has a wealth of information about the negative impacts of light pollution and smart lighting solutions at

  2. I as well remember some wonderful star filled night skies in Texas parks and specifically remember an information board in the Enchanted Rock State Natural Area that told about light pollution. That is where I first heard about the downward facing shielded lights but thank you for clarifying the concern that many people may have about safety. I hadn’t thought about that before!

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