Arizona's Night Sky: Illuminating Light Pollution

Arizona is known for its efforts to combat light pollution, with many of its cities and communities designated as Dark Sky Places by the International Dark-Sky Association. The state boasts 20 dark sky areas, 13 Dark Sky Parks, and numerous observatories that invite visitors to stargaze through high-powered telescopes. However, light pollution remains a concern in some parts of Arizona, with increasing population growth and lighting demands threatening to disrupt the natural night sky. The state and local communities have implemented various measures to mitigate light pollution, such as lighting ordinances and regulations, to protect their dark skies and stargazing opportunities.

Observatories and planetariums

Arizona has a rich history of observatories and planetariums, with its clear skies, diverse landscapes, and low humidity making it a prime location for stargazing. The state has actively worked to combat light pollution, with Dark-Sky Places designated across Arizona.

One of the most famous observatories in Arizona is the Lowell Observatory in Flagstaff, which has a long tradition of studying celestial bodies and was where Pluto was discovered in 1930. The observatory offers state-of-the-art telescopes for visitors to use, including the famous Clark Telescope, as well as interactive exhibits and historical tours.

The Kitt Peak National Observatory, located in the Tucson Triangle, has been welcoming visitors since the 1950s and is one of the first stargazing spots in Arizona. The Whipple Observatory atop Mt. Hopkins and the Mt. Graham International Observatory are also part of the Tucson Triangle, offering incredible views of the night sky.

The Mt. Lemmon SkyCenter Observatory is another popular destination, offering exhibits, a gift shop, and planetarium shows such as the "Season of Light", which explores the winter solstice and the history of various cultural traditions.

The Dorrance Planetarium, located in the Arizona Science Center, is one of the most technologically advanced planetariums in North America. With an 18-meter diameter, 8K+ resolution LED dome, it provides an immersive experience, combining art and music with astronomy.

Arizona's commitment to protecting its night skies and its variety of observatories and planetariums make it an ideal destination for both amateur and professional stargazers.

Dark Sky Week

Arizona is one of the top states in the country to experience the world's natural starry skies. The state has long fought against light pollution, and its dark skies can be enjoyed in many locations across the state. The International Dark-Sky Association has designated 20 dark sky areas across Arizona.

International Dark Sky Week is a worldwide event that draws attention to light pollution and its harmful effects on human health, the environment, energy waste, crime and safety, and our heritage of night skies. It promotes simple solutions to mitigate the issue and celebrates the irreplaceable beauty of a natural night. The event was started by high school student Jennifer Barlow in 2003 and is now spearheaded by DarkSky International.

During this week, people are encouraged to turn off all unnecessary lighting indoors and outdoors to reduce light pollution and improve the viewing of the night sky. Participants can also take a home lighting assessment, sign the DarkSky pledge, or submit a proclamation in their community.

International Dark Sky Week is held annually during the week of the new moon in April (Global Astronomy Month), when night skies are at their darkest. The next event will be held from 21-28 April 2025.

Arizona's Efforts Against Light Pollution

Arizona helped birth the dark-sky preservation movement when, in 2001, the International Dark-Sky Association designated Flagstaff as the world's first Dark Sky Place. Flagstaff was recognised for its leadership in outdoor lighting policy and its commitment to regulating light pollution. Since then, eight other Arizona communities have earned Dark Sky status, and the state boasts 13 Dark Sky Parks.

Observatories in Arizona, such as Kitt Peak National Observatory, Whipple Observatory, and Mt. Graham International Observatory, invite visitors to explore the ink-black skies through high-powered telescopes.

By enacting local legislation and banding together, communities in Arizona have made significant strides in light pollution advocacy and protection of the nighttime environment.

Light pollution maps

Arizona is known for its efforts to combat light pollution, which is the glare from city lights that obscures the night sky. The state has long fought against light pollution, and in 2001, the city of Flagstaff was designated as the world's first Dark Sky Place by the International Dark-Sky Association (IDA). Flagstaff has been recognised for its leadership in outdoor lighting policy, with 90% less light pollution than other cities of its size.

Since then, eight other Arizona communities have earned Dark Sky status from the IDA: Sedona, Camp Verde, Big Park (Village of Oak Creek), Cottonwood, Fountain Hills, Thunder Mountain Pootseev Nightsky, Bisbee, and Tubac. Additionally, Arizona boasts 13 Dark Sky Parks, which are lands with "exceptional quality of starry nights and a nocturnal environment that is specifically protected for its scientific, natural, educational, cultural heritage, and/or public enjoyment." The most famous of these is Grand Canyon National Park, where visitors can experience the stunning night sky.

Southern Arizona is home to several observatories that invite visitors to explore the ink-black skies, including the Kitt Peak National Observatory, Whipple Observatory, and Mt. Graham International Observatory. The state also hosts Dark Sky Week, encouraging people to turn off the lights and appreciate the beauty of the night sky.

Despite these efforts, light pollution remains a concern in some areas of Arizona. For example, the Fred Lawrence Whipple Observatory (FLWO) in Pima and Santa Cruz County has implemented reasonable outdoor lighting codes to minimise light pollution's impact on astronomical research and the night sky experience. However, vigilance is necessary to ensure that light pollution is kept under control as the population grows. Additionally, proposed projects such as the Rosemont Copper Project have raised concerns about light pollution, dust pollution, and vibrations due to blasting.

Dark Sky Places

Arizona has long fought against light pollution, and the state is equally spectacular when the stars come out. The Grand Canyon State has long attracted individuals wishing to enjoy, study, and preserve dark skies. In 1988, two Tucson residents—amateur stargazer Tim Hunter and professional astronomer David Crawford—teamed up to found the International Dark-Sky Association (IDA). The state has an average of 350 clear nights per year and, as a result, some of the best stargazing in the country.

The IDA's International Dark Sky Places program recognizes sites that are using “responsible lighting policies and public education” to preserve and protect night skies. There are over 20 dark sky locations in Arizona, encompassing cities, communities, national parks, and urban night skies.

The world's first Dark Sky Place was designated in 2001 in Flagstaff, Arizona, for the city's commitment to protecting its stargazing-friendly night skies. Flagstaff's night skies have 90% less light pollution than other cities of its size – the Milky Way is visible from nearly everywhere in this city of ~70,000 residents. Eight other Arizona communities have earned Dark Sky status from the IDA: Sedona, Camp Verde, Big Park (Village of Oak Creek), Cottonwood, Fountain Hills, Thunder Mountain Pootseev Nightsky, Bisbee, and Tubac.

Arizona also boasts 13 Dark Sky Parks, defined by the IDA as lands with "exceptional quality of starry nights and a nocturnal environment that is specifically protected for its scientific, natural, educational, cultural heritage, and/or public enjoyment." The most famous of these is Grand Canyon National Park, where remarkably beautiful night skies lend draw-dropping credence to the Park Service's reminder that "half the park is after dark." Other Dark Sky Parks in Arizona include Parashant National Monument, Kartchner Caverns State Park, Tumacácori National Historic Park, Petrified Forest National Park, and more.

Southern Arizona has many observatories that invite visitors to explore the ink-black skies through high-powered telescopes. Observatories in the state include Kitt Peak National Observatory, Whipple Observatory, Mt. Graham International Observatory, and Lowell Observatory.

Legislation and bills

Arizona has enacted some of the most comprehensive lighting ordinances in the country due to its large astronomy industry. The state has enacted legislation to reduce light pollution and protect its observatories.

For example, outside lights brighter than 150 watts must be shielded in Arizona, and D2DHg (dusk-to-dawn mercury vapour) lights are prohibited by law as of 1 January 2011. Maricopa County also has specific zoning ordinances in place to deal with light pollution. Residents of the county can request a light shield be installed on streetlights that intrude on their property, free of charge.

In addition, Pima and Santa Cruz County are protected by reasonable outdoor lighting codes to minimise the impact of light pollution on astronomical research and the experience of the night sky.

The Rosemont Copper Project Environmental Impact Study (EIS) is another example of legislation that aims to protect observatories in Arizona by creating exclusion circles around them and restricting electronic billboards to the Phoenix area.

While these are positive steps, concerns remain about light pollution in Arizona, particularly as the population grows. Discussions are ongoing with various agencies and organisations to address these issues.

The negative impacts of light pollution are becoming increasingly recognised worldwide, and more cities are taking steps to mitigate it. This includes legislating or updating ordinances related to lighting standards to reduce the harmful impacts on human health, the environment, and energy consumption.

Frequently asked questions