Overview of the Problem:

The image above shows the North American night sky as seen by satellite. It vividly displays how much artificial light goes straight up into space. An estimated $1 billion of electricity is wasted every year by bad lighting in the United States alone. The purpose of night-time lighting is, with few exceptions, to illuminate objects on the ground. Properly shielded lighting fixtures (now required in many municipalities) prevent this type of waste.

If you’d like to see the entire global image from which this North American image was cut, just click on it.

To learn more about light pollution and proper light shielding, visit the website of the International Dark-Sky Association (IDA) at:

The documents below will give you some ideas about how to engage a neighbor with an offending yard light. The two contain essentially the same information, but the second is a bit more technical. Before you file a complaint with Planning and Zoning, try to start a friendly dialog first.

From UW Madison: Neighbor-1.pdf (425k)
From IDA: Neighbor-2.pdf (1372k)

Wherever you live, you can find links to your local lighting ordinances here:

Arizona Solutions:

Dark skies are a precious natural resource, and they are endangered. Astronomy brings millions of dollars into our state each year via professional research and tourism. To protect our dark skies, lighting ordinances have been enacted in many jurisdictions. If you feel you are a victim of light trespass, there may be a remedy. You need to familiarize yourself with the law. It is up to you to know your rights. It is the responsibility of your local Planning Department to enforce these lighting laws. Links to some Arizona ordinances are provided below:

Arizona Revised Statutes, Title 49 – The Environment, Chapter 7 – Light Pollution: ARS-49-7.pdf (64k)
Maricopa County Zoning Ordinance (lighting): MCZO-1112.pdf (53k)
Maricopa County Zoning Ordinance (signage): MCZO-1401.pdf (516k)
Yavapai County Zoning Ordinance: YCZO-603.pdf (89k)
Cochise County Zoning Ordinance: CCZO.pdf (564k)

Here are the phone numbers of contacts for reporting bad streetlights or insensitive neighbors. If your problem is with a nearby streetlight that intrudes on your property, you can request a light shield to be installed and better direct the light (a generous option provided at no cost to you).

City of Phoenix street lighting request line: 602.495.5125
APS street lighting: 602.371.6134
Maricopa County Planning & Development: 602.506.3011
Yavapai County Planning & Zoning: 928.771.3200

Or, if you’re really in a hurry, and in Maricopa County, you can submit a violation complaint form online at:

Complaint Confidentiality:

Complaints about code violations are a matter of public record. Although normally classified as “confidential,” the name of the complainant will be released if so ordered by a court of law. The online complaint form requires both your name and email address. However, if you are truly paranoid, be aware that the Maricopa County site does state they act on anonymous complaints as well. Of course, this would require either a letter or a phone call on your part.

The Worst Lights:

The single worst offending light is what we call D2DHg (dusk-to-dawn mercury vapor) lights. Their blue spectrum causes the light to scatter strongly in air, contributing to overall sky glow even when not line-of-sight. These lights are prohibited by law as of Jan 1 2011, but there are still many in use. Replacing these offenders are unshielded incandescent and halogen lamps. In Arizona, ANY outside light brighter than 150 watts is required to be shielded. But many are not. In 1997, DFAC co-founder Dan Heim wrote an article entitled “The Top 10 Reasons for Not Installing a Dusk-to-Dawn Yard Light.” It was first published in The Desert Advocate newspaper that same year, and reprinted many times since. Even after all the D2DHg lights are gone, the environmental impact of bad lighting will persist. Get Heim’s article, copyright-free, distribution unlimited, here:

BadLight.pdf (35k)

Dan’s motto is: The only good night lights are billions of miles away.

Additional Resources:

The IDA has a page that lets you search for approved outside lighting fixtures. If you’re looking to add or change an outside light, go here:

For a more scientific discussion of what really qualifies as “dark” skies, see this excellent explanation by Brian Skiff of Lowell Observatory in Flagstaff: