Atlanta

Creating a City for the Stars

Many Americans have never seen the night sky. Sure they’ve seen the Moon, they’ve probably seen Venus, and perhaps they’ve even been able to identify the Orion constellation. While this collection of astronomical objects is impressive, it paints an astonishingly limited portrait of our universe. Viewing the universe in this capacity is like viewing the Grand Canyon from the window of your hotel room in downtown Phoenix.

Due to light pollution, most city residents experience this limited perspective. As America and the rest of the world becomes increasingly urbanized, more people are growing up having never actually witnessed the true view of the universe from Earth. While it may seem inconsequential, this deficiency could have a profound impact on how we interact with ourselves, our communities, and our planet.

As the great Carl Sagan said while reflecting on an image of the Earth taken by the Voyager 1 spacecraft 6 billion kilometers away:

“…Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity – in all this vastness – there is no hint that help will come from elsewhere to save us from ourselves. It is up to us. It’s been said that astronomy is a humbling, and I might add, a character-building experience. To my mind, there is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly and compassionately with one another and to preserve and cherish that pale blue dot, the only home we’ve ever known.”

 

Pale Blue Dot

Voyager 1’s Pale Blue Dot photograph. Earth is the tiny dot in the orange band on the right.

 

Light pollution severely restricts our ability to experience and appreciate our universe. It isn’t necessary to see a photograph of Earth from 6 billion kilometers away to have the same humbling experience as Carl Sagan. Simply gazing up at the stars from a bedroom window, a backyard, or a community park could elicit the same appreciation, curiosity, and desire for scientific exploration. However, many Americans never have this opportunity because the night sky is obstructed by light.

Sriram Murali has created some beautiful time-lapse videos showing the night sky at various levels of light pollution. In reflecting on the impact of light pollution on city dwellers, he echoed many of Sagan’s points:

“The night skies remind us of our place in the Universe. Imagine if we lived under skies full of stars. That reminder we are a tiny part of this cosmos, the awe and a special connection with this remarkable world would make us much better beings — more thoughtful, inquisitive, empathetic, kind and caring. Imagine kids growing up passionate about astronomy looking for answers and how advanced humankind would be, how connected and caring we’d feel with one another, how noble and adventurous we’d be.”

Beyond limiting our understanding and appreciation of the universe, pervasive light pollution negatively affects human health and wastes energy. It disrupts our circadian rhythm, which regulates sleep behavior. It potentially inhibits the healthy growth of plants and discourages the movement of pollinators. Using bulbs or fixtures that produce unnecessary or excessive light is a profound waste of energy, which can be a significant financial and environmental cost. To many in denser areas, it can simply be annoying to have a neighbor’s light pointed directly at your window or porch.

Cities and States Need to Take Action

Though we can’t completely eliminate light pollution, we can take action to reduce pollution levels and mitigate further increases. At the state level, we can pass light pollution laws that provide basic lighting guidelines. As of 2016, 18 states had various statutes governing light pollution. Arizona, a magnate for astronomers, has prohibited un-shielded outdoor lights since 1986. Florida has a model lighting ordinance that coastal municipalities can use to shield hatching turtles from light pollution. A collection of other states, from New York to Arkansas, have statutes requiring shielded and downward facing lights on all public properties. While the main purpose of the statutes may be to combat light pollution, they also serve to reduce wasteful energy spending by requiring light to be focused where it is actually needed.

Georgia has no such laws, though we do have Stephen C. Foster Park, one of the only gold-tier International Dark Sky Parks on the east coast.

Cities can also pass more comprehensive lighting ordinances. The International Dark Sky Association (IDA) and the Illuminating Engineering Society (IES) provide a model lighting ordinance that regulates the type and location of lights. While a state statute may provide general guidelines or only apply to public buildings, a local ordinance can aggressively combat light pollution.

The IDA and IES model ordinance recommends dividing a city into lighting districts, each with different regulations regarding light output (measured in lumens) and light positioning. Higher density commercial areas would have a higher cap on lumens than a low-density residential zone, though similar restrictions on upward facing and un-shielded lights would generally apply in all zones. Another important restriction designed to reduce energy costs is the implementation in the ordinance of automatic shutoff devices for lights during daylight hours. Tucson/Pima County has a similar zone-based lighting ordinance to prevent light pollution from venturing into the pristine stargazing areas just outside the city.

Orion Constellation

The Orion Constellation as seen through medium light pollution (left) and low light pollution (right). Left image credit: Gustaaf Prins. Right image credit: Anton Vakulenko

It appears Atlanta only regulates lighting in three capacities: parking lots, storefront illumination, and the up-lighting of trees. Parking lots can have no more than 1 lumen per square foot; in certain districts storefront lighting is prohibited from spilling into adjacent properties; and lights pointed upwards must be 8 feet above the ground. The model lighting ordinance would severely limit upward pointing lights in all districts and would limit lumens for an entire parking lot (not just on a per square foot basis). Atlanta’s 1 lumen per square foot, though, is in-line with ordinance recommendations. While it’s good that the city has recognized some restrictions, Atlanta and our suburban municipalities need comprehensive schemes for requiring all land uses, not just parking lots, to consider lighting. This could also include the protection of our tree canopy as trees can prevent ground-based light from obstructing the night sky.

In the effort to create cities and communities that foster inclusiveness, cooperation, and curiosity we should consider the impact of a clear night sky. While a lighting ordinance certainly wouldn’t eliminate light pollution, it could significantly improve your ability or your child’s ability to see much more of the universe.

 

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