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LIGHTING MYTHS
by Tim Hunter and Dave Crawford
The International Dark-Sky Association (IDA), Inc.
INTRODUCTION
Most amateur astronomers are aware of light pollution and light
trespass, and many amateurs are working hard to improve the
night sky conditions in their communities. They often come
across a variety of objections, which are usually based on
inaccurate facts, misconceptions or, at times, deliberate
falsehoods. Many of the objections to improving our night skies
should be categorized as "lighting myths." Some of the more
common and egregious myths are summarized below. Those who want
to fight light pollution and light trespass should become
particularly familiar with these myths and learn the actual
facts behind them.
THE MORE LIGHT THE BETTER
"The more light the better" is the same type of reasoning as
saying the more salt on your food the better, or the more
fertilizer the better, or the more medicine the better.
Obviously, there comes a point where you can have too much of a
good thing. Eventually, it becomes wasteful and harmful.
Nighttime lighting behaves in the same way. We all need well lit
main streets, security lights, and parking lot lighting.
However, we do not need glare, clutter, confusion, light
trespass, light pollution, and energy waste. Excessively bright,
numerous, unshielded lights cause exactly these things.
You
only need enough light to perform the task at hand. For example,
you use low watt colored bulbs for Christmas tree lights, and a
100 watt bulb for a porch light. If more light were better, why
are night lights in a bedroom dim instead of bright? The next
time you are at an airport at night look at the brightness of
the taxi lights (blue color) or the runway lights (white color).
They are relatively dim so as to not harm the pilot's night
vision and cause confusion. Even the rotating airport beacon is
not especially bright. The strobe lights on tall chimneys and
radio towers are of low wattage, yet visible for miles. Those
who claim the more light the better often are salesmen or
manufacturers more interested in sales than effective, safe,
environmentally sound lighting.
The Illuminating Engineering Society of North America (IES or
IESNA, 120 Wall Street, 17th Floor, New York, NY 10005) is the
main professional organization for lighting engineers in this
country. The IES publishes many information books for lighting
professionals and has established sets of recommended lighting
levels for various applications. For nighttime sports
activities, these recommended levels may be quite high, but for
security lighting in a rural area with little activity, they
will be quite low. The IES recommended lighting levels are not
the absolute answer for every lighting situation or need, but
they are a good start for most occasions requiring a reasonable
amount of nighttime lighting. In general, it is a good idea for
a lighting application not to exceed IES recommendations,
because this will usually lead to wasted energy and possible
light pollution, light trespass, and glare.
The International Dark-Sky Association, Inc. (IDA) is a
sustaining member of the IES and believes very strongly in the
professional approach the IES takes toward lighting
applications. Most of the individual members of the IES make
their living designing indoor and outdoor lighting systems, and
many of them are familiar with IDA. Most professional outdoor
lighting engineers who are members of the IES are supportive of
IDA's goals.
LIGHT POLLUTION ONLY AFFECTS ASTRONOMERS
Light pollution affects all of us. It robs the professional
astronomer of a livelihood and hinders the amateur's enjoyment
of a hobby, but it deprives everybody of the awesome grandeur of
the night sky. Many persons who claim this is of no importance
have never gone far enough out of town to see what they are
missing. Those who grow up in an urban environment may never see
the Milky Way. How can someone miss something he or she has
never seen?
The loss of the night sky desensitizes us to other insults upon
the environment. It's the same as saying the loss of a virgin
forest is of no concern, because most people don't live in the
woods, and there are plenty of trees elsewhere. The loss of wild
flowers, polar bears, wolves, whales, and other threatened
species, to be honest, won't affect the average person. Their
loss only directly impacts biologists who study them. After all,
mankind has done very well without mammoths, mastodons, and
passenger pigeons.
No one supports extinction of magnificent animals. Why should we
permit extinction of our skies? Everyone has a right to the
stars. Light pollution is the earliest and most visible sign of
environmental destruction. The dome of light hanging over most
cities blots out the stars, and electricity is wasted to light
the night sky -- light needs to be on the ground not up in the
sky. The wasted electricity represents needless burning of coal,
oil, and natural gas, whose byproducts show up as acid rain,
smoke, and carbon dioxide emission. Strip mining and underground
mines produce the coal used for much of the wasteful burning, and runoff from
this mining pollutes rivers and streams.
Thus, light pollution is far more than some astronomers being
inconvenienced. It is a most harmful assault on the environment.
It affects us all, and all of us ought to be concerned about it.
JUST GO OUT OF TOWN, AWAY FROM THE LIGHTS
This is equivalent to saying why worry about the loss of trees
and flowers in our cities. Why have urban parks? Just go out of
town to see some grass, flowers, or trees. It shouldn't be
necessary to go out of town to see them. If we can't have enough
sense to plant trees, shrubs, and flowers all around our cities,
we can at least have enough sense to plan for parks and preserve
those green areas left. Why not have the same attitude toward
dark skies? We are not asking people to turn off their lights.
We are asking them to shield their lights, use proper lighting
levels for the lighting task at hand, and turn off unneeded
lights.
In any event, it is no simple task to get away from the lights.
Urban sky glow, the dome of light hanging over all cities of any
substantial size, extends for miles and miles. For example, it
is easy to see the sky glow of Phoenix, Arizona, from more than
100 miles away. The sky glow from Los Angeles, California, is
visible from an airplane 200 hundred miles away. How many dark
spots are left in the urban corridor in the Northeastern part of
the United States? Even in the most remote portions of North
America, there are dusk to dawn lights blaring into the
darkness. The light from one of these causes significant light
trespass a mile or more away. We challenge anyone reading this
essay to find a mountain top or plateau in the continental
United States where there is no trace of light pollution visible
somewhere on the horizon.
IT'S TOO LATE TO DO ANYTHING ABOUT LIGHT POLLUTION - THERE
ARE TOO MANY LIGHTS
This is a frequent response when we ask people why they are not
more active in the light pollution struggle, and it's tough to
answer. Yes, the problem is enormous, growing in many areas, and
very difficult to grasp fully. This doesn't mean it isn't worthy
of effort. We have barely begun to fight. Just because we have a
very big problem on our hands and presently few resources to
bring to bear, doesn't mean we can't ultimately win. It's way
too early in the struggle to say it's impossible to do anything
about light pollution. Only recently has a small fraction of the
public and astronomical community awakened to the problem. Only
recently have we realized there are solutions to most lighting
difficulties. There are now excellent fixtures available for all
lighting needs. This is one of those few problems whose solution
is eminently sensible, available, and saves money in both the
short and long terms.
If you expect to rid a large city of its sky glow in the next
year, then you will be very disappointed. If you want to get rid
of local sources of light trespass, such as a dusk to dawn light
next door or an unshielded street light on the corner, then you
have a very good chance of accomplishing your goals with
persistent but not obnoxious effort. You also have a reasonable
chance for changing laws and instituting proper lighting
techniques in your community. Over a long period of time, good
lights will replace the bad ones. There will be a gradual
slowing of the loss of dark skies and then an actual darkening
of skies in some areas. This will not happen quickly, but it is
possible. It will take incredible amounts of work and
determination, but it can be done.
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