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Paper Plate Education
"Serving the Universe on a Paper
Plate"
Light Pollution
Light pollution is impinging on the quality of our night skies
as wasted light results in glare, light trespass, and skyglow. Many people
simply are not aware of the problem, which can be corrected with better light
fixtures while saving significant energy and money. The two simple
demonstrations below (borrowed from an 8-year old) show
how effectively a full shield over a bare light bulb can improve the ground
lighting while reducing wasted light.
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To simulate an unshielded light on a pole, place a Maglite®
flashlight in the free-standing "candle mode" on a white
surface. |
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Turn off all lights and observe how the light spreads
out. Look up at the ceiling, too, to see the light lost to the
sky. Note how the flashlight base obstructs the light in a cone of
darkness, and how the exposed bulb glares brightly in your eyes. |
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Now cover the exposed light with different shields and see
what material improves the situation. While not practical, covering
the bulb with just a hot pizza is a significant improvement. |
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Shields made from various materials--a pair of hands, a
paper plate, a pie tin, and a hot pizza-- always improve the
situation. Note how the text under the shadow cone becomes clearly
visible.
You get several positive outcomes with full shields:
- Light is directed downward to where it is wanted, so lower wattage
bulbs can be used, thus saving energy and money.
- Direct glare does not impair night vision or cause light trespass.
- General light pollution overhead ("skyglow") is lessened.
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Here is another simple illustration--again
borrowed from an 8-year old.
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Prop open a book that has a picture of a landscape. In
this case, the view is of the Chicago skyline, with street lights in the
foreground. Place a Maglite® flashlight in the free-standing
"candle mode" in the foreground. Here we put the
flashlight so it coincides with the street light on the right. Also
place a figurine in the scene. |
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Turn off the room lights. Note how the figurine is in
the shadow cast by the exposed light. Glare is obnoxious.
Objects, like parked cars, are barely seen in the darkness beyond the
glare. The sky is aglow with wasted light. |
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Now cover the light fully with a paper plate shield. The figurine
and surrounding area is brightly illuminated. Glare is
eliminated. Objects, like the parked car, are now visible beyond the
light fixture. And the sky is dark. |
Contributed by Sarah B., age 8.
These activities are featured in the Let There Be Night program
at www.LetThereBeNight.com. See also www.nightwise.org.
[Added June 2009]
See the use of paper plates in these other activities that
address outdoor lighting issues:
- Activity: Turtle
Hatch (The Night You Hatched)
Demonstration shows the survival challenges of turtles (simulated by large
group of kids) hatching on a beach at night. Ask your school's Student
Leadership Team to partner with you for this fun demonstration.
- Activity: Globe
at Night
Students use a starfield of Orion (drilled into a stack of paper plates)
to help students find and count the stars of Orion for Globe at Night.
- Activity: Heavens
Above
Students draw their impression of night sky highlights to show what's at
risk of being lost because of light pollution.
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