Disappearing sky: light pollution from Phoenix threatens astronomy industry


Picture from the International Space Station of Tucson (right), Phoenix (center) and Las Vegas (upper left). Courtesy of International Dark-Sky Association.
Picture from the International Space Station of Tucson (right), Phoenix (center) and Las Vegas (upper left). Photo courtesy of International Dark-Sky Association.

Arizona is one of the best places in the world to see the stars but its stargazing nights might be numbered.

Light pollution primarily from Phoenix is degrading the night skies, diminishing the visibility of the heavens that has fueled a multimillion-dollar astronomy industry.

Arizona’s clear weather, dry climate and high mountains make the state ripe for observatories. The state boasts 30 of them, mostly around Flagstaff and Tucson.

The problem occurs when telescopes are pointed in the direction of Phoenix, which can project light for hundreds of miles in every direction and can be seen by observatories as far as Kitt Peak. Phoenix casts more light because of its sheer size but the lighting is denser than in a city like Tucson or Flagstaff, which have strict lighting ordinances.

City lights lower the visibility of the universe by casting a yellow glow over the stars.

Picture from the International Space Station of Tucson and Phoenix. Courtesy International Dark-Sky Association.
Picture from the International Space Station of Tucson and Phoenix. Photo courtesy of International Dark-Sky Association.

“When we point the telescope in that direction in the atmosphere above a major metropolitan area, the background, the light that’s scattered in our own atmosphere, starts to overwhelm some faint astronomical source that’s behind that,” says Grant Williams, director at the MMT Observatory.“From the prospective of the observatories, we’re interested in good outdoor lighting, and when outdoor lighting is done properly it benefits everybody.”

The International Dark-Sky Association founded in Tucson in 1988 is dedicated to educating the public and help draft ordinances for cities. Currently the IDA is working with Malibu, California, on drafting a lighting ordinance.

“There has been really a greater attention here to make sure they are doing the right thing on outdoor lighting,” says Scott Kardel, the association’s acting executive director.

For decades counties and municipalities in southern and northern Arizona have been preserving the skies by passing city light ordinances; Pima County adopted the first outdoor lighting code in 1972. Phoenix has fallen behind because no major observatories are in the area and the city is more concerned with promoting business.

Flagstaff produces around 2,500 lumens per capita without sports lighting where as Phoenix produces 3,200 lumens per capita. The difference is in the strict lighting codes Flagstaff has adopted over the years.

The astronomy industry brings Arizona around $250 million annually and more than 3,000 jobs. The state has also made an investment around $1 billion in the astronomy industry.

Other states like Hawaii compete with Arizona for astronomy tourism and related businesses. Flagstaff is in the running for the Cherenkov Telescope Array or CTA, an array to measure gamma rays in the universe. It would be one of the flagship ground-based observatories and would be a $130 million investment according to Jeff Hall, Director at Lowell Observatory. The decision to place the CTA in Flagstaff could be severely impacted by the sky glow from Phoenix according to Williams.

The millions of dollars a year the astronomy industry brings to Arizona also comes from public tourism.

“You’ll realize our eyeballs are terrible,” says Adam Block, public observing manager at the SkyCenter, which has the 32-inch Schulman telescope, the biggest publicly dedicated telescope in the country.

Block has met people from as far away as Estonia who have come here to view our skies.

The SkyCenter, along with other observatories, allow the public to get their hands on powerful telescopes. The SkyCenter charges anywhere from $30 to $60 to see what it is like to be an astronomer.


Contact reporter at bvalencia@email.arizona.edu

2 comments Add yours
  1. Thanks for publishing “Disappearing Sky”. Articles like this serve us all by bringing the issue of light pollution to the attention of the public. The problem only persists largely due to lack of awareness. When people become informed, see the simple win-win solutions, they become active in protecting the night sky.

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