Some light reading about all the stars we cannot see in Denver
When was the last time you saw the Milky Way? If you’re staying in Aspen you just might see that magical celestial arc, our galaxy of stars, once again. That’s because the mountain town known for skiing and Hollywood sojourners has adopted an ordinance to cut down on the use of artificial lighting at night which obscures the stars and harms the health of creatures great and small.
The Aspen law requires businesses and homeowners to ensure their indoor and outdoor lighting does not shine past their property. They must also observe a light curfew, 10 p. m. to 7 a. m. or an hour past closing or before opening in the case of businesses that keep night hours. Light trespass can be curtailed by turning off lights, dimming or shading lights, and using motion detectors for outdoor security, pathways, and seasonal lighting. The lighting of streets and parking lots can be reduced by proper angling, shading, and using warm rather than blue light.
According to astronomers, Metro Denver is 100 times brighter than natural darkness. The city and other Front Range communities should adopt a similar ordinance to reduce the harmful impacts of light pollution, save energy, curtail carbon emissions, and bring back the stars.
Studies show that artificial light at night elevates risks for sleep disorders, obesity, depression, diabetes, heart disease, and cancer in human beings. It also negatively affects animals active at night. In North America, 80% of the continent’s birds migrate every spring and fall mostly by night. Artificial lighting disrupts their navigation and draws them into urban environments where there less food and a higher likelihood of colliding with a building. A billion birds die in North America alone from such collisions.
Night lighting also disrupts the lifecycles of nocturnal insects, mammals, reptiles, and amphibians. Light pollution, along with habitat loss, pesticides, and air pollution, has reduced insect populations worldwide. Insects are no less extraordinary than larger and more charismatic species. They are also essential for pollination and as food sources for larger animals. Their decline imperils ecosystems.
Wasted light also wastes energy. Darksky, an organization that advocates responsible night lighting, estimates that outdoor lighting in the US consumes 120 terawatthours of energy which is enough to power New York City, population 8.4 million, for two years. That could power Denver Metro Area with its 3 million people for six years. According to the organization, roughly 30% of outdoor lighting is wasted. Each year lost light costs the nation $ 3.3 billion and results in the discharge of 21 million tons of carbon dioxide.
Some outdoor lighting is essential for safety and enjoyment. More is not better. In areas where safety is a concern, bright light actually creates more glare and deeper shadows and reduces safety. Dimmer lights are better achieving visibility.
Simply by shading outdoor lights, angling them properly downward, and using warm rather than bright high intensity LED lightbulbs, Front Range cities and suburbs could drastically curb energy use, save money, and reduce carbon emissions. Such a reduction would help Denver, which has committed to eliminate greenhouse gas emission by 2040, to meet its goals.
Lights Out Denver, an initiative of Denver Parks and Recreation, encourages building owners and managers to reduce nighttime lighting, particularly during bird migration seasons, and collects data on bird collisions. It is not enough to encourage; like water and air pollution, light pollution is a negative externality that needs regulation. For the sake of humans and animals, night lighting should be limited and purposeful, not ubiquitous and habitual.
Rural small towns like Westcliffe and small cities like Aspen have committed to restoring the night sky and Boulder and Fort Collins have taken some steps to limit wasteful outdoor lighting. The Denver Metro Area is the brightest spot on the Colorado map. It’s time to dim the lights and see the stars.