Paul's Note - December 11th, 2020

Southern Arizona hosts the world’s largest optical telescope and 10% of all the world’s largest telescopes. The Department of Energy, the National Science Foundation, the Smithsonian Institution and NASA, along with US universities and foreign institutions, invest tens of millions of dollars annually in the operation and upgrade of the Southern Arizona observatories. A basis for their long-term scientific investment strategy is their perception of the commitment of local government to protecting that national and international investment. All told, there are more than 3,000 people employed in some way by our local observatories. 

Also, it’s a point of pride to read in the news about a discovery of a new star cluster or moon and see that the work was done here in Southern Arizona. 

The presence of those observatories is a big reason for our local optics industry, which employs an additional 1400 local residents in well paying jobs and results in $600 million for our local economy. 

There is also a growing tourist industry not only connected to the observatories, but also to people who seek out dark skies to observe events like big meteor showers or just a trip to go star gazing. 

The importance of this industry came up on Tuesday when Mayor and Council were discussing changes in the sign code, as well as getting rid of the “sunset” period that allows for regular review of the sign code by mayor and council. The astronomy industry is concerned because, as noted in a letter from the Arizona Astronomy Consortium that was sent to me and my colleagues: 

Major revisions to the City Sign Code in 2017 included incentives for the proliferation of electronic message displays (EMDs), which are particularly damaging to dark skies at observatory sites. State Statute bans that very technology as offsite billboards, precisely because their operation is so detrimental to dark sky preservation. 

Electronic Message Centers is the term we use in sign regulation to call a sign that displays a message that can be changed. Our current code allows for them, but we put restrictions on them. 

One thing to know about EMCs is that they tend to be brighter than other signage. The industry and regulators talk about a self-illuminated sign’s luminescence and measure it in nits. You can think of typical traffic lighting being around one nit. According to data collected by Scenic America on a study of Arizona’s billboards, the typical lighting of one billboard is usually 100 nits. 

The luminescence on an EMC can be as high as 8500 nits. By comparison, a sunny day is 5000 nits. 

Our current lighting code call for shielding of lighting so that we can maintain a dark sky. However, even with shielding, at those levels there will be a significant amount of light trespass, that is, light that spills on to neighboring properties and up to the sky to obliterate our view of the stars. 

The professional astronomers who sent who sent us the letter also highlighted that: 

The restoration of the natural desert sky would benefit not only astronomy but also tourism and residential property values, core elements of the economic vitality of the City. 

We have rules in place to limit the hours and use of EMCs now, but as I pointed out at the meeting, these are difficult to enforce. Changes that encourage more of them to be installed will only make those rules harder to enforce. I also opposed getting rid of the “sunset” provision because we have a city-county committee working on new standards. We need to let that committee do it’s work before we make any major changes. 

Our local dark skies and astronomy are things that makes Tucson special. Let’s protect them.