Could landscape design block the stars? Email

Can’t see the Milky Way? You have lots of company—says a 2016 study published by the American Association for the Advancement of Science. The cause is light pollution.

Light pollution— really?
Like any other form of pollution, it disrupts ecosystems, has adverse health effects and is caused by humans. Light pollution alters night lighting with excessive artificial light.

Only in the last several years have environmental scientists started studying the effects. They consider light pollution to be the most pervasive form of environmental alteration affecting even the most pristine sites with limited human contact, such as Death Valley National Park in which the glow of light domes is seen from as far away as Los Angeles and Las Vegas. Five years of satellite imagery show global light pollution is increasing.

Environmental effects
Light pollution is not just an issue for nerdy astronomers. When biological processes and ecosystems are negatively affected, we need to pay attention.

Think pollinators. Light at night decreases the number of nocturnal pollinators such as bats, moths and beetles, reducing the yield from agricultural and medicinal plants.

Artificial lighting has been shown to misdirect newly hatched sea turtles, preventing them from reaching the safety of the ocean. For humans, light at night disrupts the body’s formation of melatonin, the natural sleep hormone.

Ways we pollute the night sky
Experts categorize light pollution into four general types:

  • Glare – excessive brightness causing visual discomfort or difficulty judging distance.
  • Skyglow – brightening of the night sky over inhabited areas.
  • Light trespass – light falling where it is not intended or needed.
  • Clutter – bright, confusing and excessive groupings of lights.

Respect the night sky with smart design

  • Choose full cutoff, shielded fixtures.
  • Select proper brightness based on lumens, not wattage. For most outdoor lighting needs, 100 to 300 lumens will be adequate. Since 2011, manufacturers have been required to state lumens for their products.
  • Choose light color with awareness of Color Correlated Temperature (CCT) and select less than 3000K, preferably less than 2700K. K refers to degrees Kelvin, a temperature scale used for rating CCT. Often packaging, even for consumer lighting, states the CCT in K. Though lower temperature LEDs require slightly more power (wattage) than higher CCT lights, for a given brightness, we recommend no more than 3000K rated LEDs.

Design to conserve resources
Light that goes up is wasted energy. International DarkSky Association estimates approximately 30 percent of outdoor lighting in the United States is wasted annually—mostly from lights that are not shielded—or roughly $3 billion of energy. About 600 million trees would have to be planted to offset the carbon dioxide emissions.

Read more in this issue of Colorado Green NOW:
Best Yard gives Parker landscape companies a home
Getting ahead of water restrictions
17,000 Front Range trees already prepped for Emerald Ash Borer

811 bill passed by Colorado legislature

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