Introduction to Lighting and Light Pollution

What are the Problems? What are the solutions?

a slide presentation
by Christian B. Luginbuhl

1 View of Flagstaff at Night from Mars Hill

This is a photo of Flagstaff at night, taken from the road to Lowell Observatory on Mars Hill. Many of us have seen this view, or a similar one. But there is more to this picture than meets the eye.

2 View of Flagstaff from US Naval Observatory

Here we see the same part of Flagstaff, more or less. But now we are at the Naval Observatory about 5 miles west of downtown. The lights are visible from a long way away. Also, if the broadcast image shows it as well as the eye can see it, you may notice a glow extending into the air over the city. The effects of our city lights spread far, across the landscape for miles and into the sky.

3 View of Phoenix from U.S. Naval Observatory

Now we turn our gaze southward, still from the Naval Observatory just west of Flagstaff but now looking toward the south. There is a glow arching over the southern horizon, over Woody Mountain. It is the Phoenix metropolitan area, over 100 miles away. The effects of our lights spread very far.

4 DMSP (weather satellite) image of USA at night

This is widespread. Wherever humans live, especially in western societies, we use light. Lots of light. This is an image of the USA taken at night from a weather satellite. Even the tiny villages of Bellemont and Munds Park, Arizona, are visible.

It seems natural to think - Well, of course! We use light at night, so why shouldn't we see this light from overhead? Isn't the ground lit up, and reflecting the light back up?

Unfortunately this reflected light is only a fraction of the light we see. Studies have shown that most of the light we see from overhead never has touched the ground. It never lit someone's way on a road, parking lot or sidewalk, never provided any aid or benefit to anyone on the ground. It shines directly upwards, into the sky.

The majority of the light we see here, more than half certainly, probably more than 3/4 of it, it pure waste. The International Dark-Sky Association estimates, very conservatively, that in the USA alone we waste over a billion dollars a year like this. This is not only money, it is also resources, mostly coal and petroleum in this country. And it is taking away our night skies.

5 Las Vegas Strip at Night

This is a view of Las Vegas:? first looking toward the Strip,

6 Las Vegas Night Sky

then toward the sky. It was an entirely clear night, the kind the desert used to be famous for. There were less than 25 stars visible here, in the entire sky. I counted.

Though few live in a town as bright as Las Vegas, nonetheless the vast majority of Americans have lost the view of the starry skies that were the heritage of their parents and grandparents, of every generation of mankind until recently. Most children today think the Milky Way is only a candy bar and something you might hear about in school. The constellations are less familiar to them than the surface of Mars; they don't know that there are planets and stars in the sky. Or if they do, they probably only see them on vacations to special places, like seeing animals in a zoo.

How does this happen? How does this light get into the sky? Why?

7 Flagstaff from Mars Hill (repeat of slide 1)

Look at this picture of Flagstaff from Mars Hill again, and think a little about what we see. We see our city; but wait a minute. Actually, most of what we see are lights.

8 Closeup of Flagstaff Lights

Very little of what we see is what the lights are supposed to be lighting - the roadways, parking lots, sidewalks. We see the lights themselves! But here on the edge of Mars Hill we are about 200 feet over the city. We are 200 feet over these lights! These lights are shining light upward toward us. This light never touches the ground; it is going straight into the sky.

Is this light doing anybody any good?

From this far away we might say that these lights, though not the most efficient, are kind of pretty. But down in the city, where people are trying to see (after all that's what the lights are for!), this light shining upwards could be shining onto the ground and helping visibility. The light that shines sideways, even if it is downwards a bit, is shining into peoples' eyes even more, causing glare that decreases their ability to see.

What does this look like close up?

9 Floodlight in a parking lot

This light is meant to illuminate a small parking lot next to a home business - you can just see the parking spaces in the foreground. But the glare from the fixture makes it very hard to see, and creates dark shadows close to the building that could very well provide hiding places for persons up to no good, hidden by the shadows and glare. It is even shining into the roadway and into the eyes of passing drivers. Is this light providing visibility or security for anyone?

10 Parking lot floodlight in daylight

In the light, it is easy to see what is wrong. If we just think about it, we can see even before we turn on this light that there are going to be problems.

11 Closeup of the floodlight in previous slide

12 Another bad example - Wallpack

Unfortunately, if you start to pay attention to lighting and how it is used, you will see that careless lighting is everywhere. Even in Flagstaff, with a long history of sensitivity to dark skies. Look around next time you are out at night, on campus but especially off campus.

But the good news is just this - the problems are really obvious, when we just open our eyes, and ask the simplest of questions about our lighting.

13 Principles of Quality Lighting

• Is the right amount of light being used? Not overkill, and not too little! We need light to see, but twice as much as we need is not better, does not provide any greater visibility or safety.
• Is the light shining where we need it? Not into the sky, not into our eyes!
• Is the light being used when we need it? If we are not using the area at 3am, do we need to leave it on? Would we leave our living room lights on all night?

These are the principles of quality lighting. It is not rocket science. The ideas can be understood by any fourth grader. If we ask these questions about our lighting, and demand that all lighting effectively and efficiently meet our needs for visibility, we will have none of the problems we have been describing.

Here are examples of lights that work with us, with our eyes, to efficiently use light, direct it where it is needed, and provide the best visibility. It seems so obvious when you think about it.

14 Fully shielded "shoebox" light over Tucson, AZ

The light from this fixture is directed downwards, not upward and not sideways.

15 Fully shielded parking lot lighting at night (Cottonwood, AZ)

Here is another example, at night. These lights give good visibility, don't cause glare and don't waste light into the sky.

16 Bad lighting at home - A "jellyjar" porchlight. Only $5.49!

At home, too, we should expect performance from our lights, not just "watts," and not just shiny brass.

17 Good lighting at home - a fully shielded porchlight

All of us can make a tremendous difference in the quality of our nighttime environment if we just apply these principles to the use of night lighting at our homes and businesses. Solving our light pollution problems is just as simple as the principles of Quality Lighting, and everyone benefits when we do. There are no losers.

18 Orion from the U.S. Naval Observatory

What do we gain?

We get better visibility on the ground - that's the whole purpose of lighting! No glare!

We slash the amount of light spraying into our skies to half or even less. We save on electrical bills and energy wasted on wasted light. We stop wasting the resources to produce this wasted light. We get our dark and starry skies back. If Flagstaff could make all of its outdoor lighting work for us, and not against us, we would get better visibility on the ground, lower energy use and bills, a more attractive nighttime community, and skies as dark as or even darker than they were when Flagstaff was only 25,000 residents.

Panel members:

• John Grahame, Flagstaff Dark Skies Coalition (FDSC)
• Wes Lockwood, Lowell Observatory
• Christian Luginbuhl, U.S. Naval Observatory and FDSC
• Al White, Flagstaff City Council

Taped 22 May 2001
Cablecast 1 June 2001
Flagstaff, Arizona

(This slide show was presented at the beginning of this First Friday program to introduce the issues. For information on the First Friday Colloquium series, including an email address from which video tape copies may be requested, click here.)

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