Let There Be Night

Let There Be Night is a combined planetarium program and school district-wide experiment to assess a community's sky glow.  Developed for IYA2009 with contributions from Toyota and other supporters, the experiment  parallels the Globe at Night initiative.  The planetarium program and DVD resources are available to prepare the teachers and students, who will assess sky glow from within the school district boundaries. See the Results from one community's vast experiment in 2009, in which teams of students made a 3-D model out of 35,000 LEGO blocks to convey visually how much of the local night sky has been lost to light pollution.   

 

Night Vision

Night Vision is a NASA-supported program in which observers quantify the sky glow over their community.  Families and teams use hand-held Sky Quality Meters (SQMs) to measure the the amount of light reflected back down to earth from multiple sites.  They will manually plot the SQM readings on a county map and create "contour lines" of equal brightness.  The baseline map can be used in the future to suggest changes in the local light pollution level.  After discussing the trade-offs of lighting technology and the social decisions related to outdoor lighting, participants will report their findings to the community through self-designed presentations.

 

Sorry Starry Night

For a science project named Sorry Starry Night, a student measured the sky glow from seven sites adjacent to a new retail development.  From March to December, 2006, she plotted a downward slope of Sky Quality Meter (SQM) readings, which suggested the sky glow increased.  The student attributed the increase to new lights from the development, additional reflectance from snow on the ground in the latter portion of the experiment, and holiday lights in the neighborhood. 

 

Paper Plate Education

How can you convey the impact of glare and the benefits of light shields?  Try this simple experiment--so easy it was borrowed from an 8-year old.  (Reproduced from Paper Plate Education, http://analyzer.depaul.edu/paperplate/lights.htm).

   

To simulate an unshielded light on a pole, place a MagliteÆ flashlight in the free-standing "candle mode" on a white surface.  

 

(No Shield)    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.

 

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.  

 

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--sky glow--is lessened.

 

Here is another simple illustration--again borrowed from an 8-year old.  (Reproduced from Paper Plate Education, http://analyzer.depaul.edu/paperplate/lights.htm).

 

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 MagliteÆ 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.  

 

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.

 

Now cover the light fully with a 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.

 

Other Projects:

 

Extended list of ideas for student projects or academic fairs, with specific reference to issues in northern Indiana.

 

http://old.nightwise.org/gsms.htm

Two students measure sky glow in their community, then share results with their classmates in a portable planetarium.

 

http://old.nightwise.org/chain.htm

Energy chain illustrates how only about 1% of initial energy makes it from generator to roadway reflection.  

 

http://old.nightwise.org/workshop.htm

A light pollution workshop at a planetarium conference was dedicated to sharing techniques for preserving the night sky.  Many of the workshop activities, taken from the perspectives of varied interest groups and stakeholders, can be used by other dark sky advocates.

 

Additional projects by other parties are described at http://old.nightwise.org/projects.htm#other:

 

http://www.globe.gov/GaN/

Globe at Night is a worldwide campaign to observe and record the magnitude of visible stars as a means of measuring light pollution in a given location.  Website has an effective simulator to show the limiting magnitudes of stars in the constellation Orion.

 

www.nasa.gov/audience/foreducators/starcount

Participate in a star count performed by Canadian Space Agency astronaut Steve MacLean aboard the Space Shuttle Atlantis in September 2006.  "Students will learn how to estimate the number of stars observed based on random samples of sections of the sky. Students will add to the database by entering their location, number of stars observed and information about their viewing conditions. The students will be able to compare their observations with MacLean's and other observers."  

 

http://www.starcount.org/

International event encourages everyone to go outside, look skywards after dark, count the stars they see in certain constellations, and report what they see online.  

 

http://www.astrosociety.org/education/publications/tnl/44/lightpoll.html  

Light Pollution, Universe in the Classroom, No. 44, Fall 1998; from the Astronomical Society of the Pacific.

 

http://britastro.org/dark-skies/education.html?2O

Pupil dilation experiments demonstrate the effects of light pollution; from the Campaign for Dark Skies.

 

 

Solutions

 

High-quality exterior lighting benefits modern society.  However, the byproduct of poor lighting installations, light pollution, is commonly seen as glare, spillover, and sky glow.  The objective is not necessarily to have less light on the targeted object, but to have better light.  Manufacturers of sky-friendly fixtures, below, offer viable alternatives to typical, offensive outdoor lights.  You have choices. 

 

What's the problem?

Why should I care?

What can I do?

 

Glare 

 

Glare is light striking your eye directly from the source.  A veil of light across your field of view reduces the contrast between objects--you can't see as well in the stark brightness.

 

For motorist and pedestrian safety, drivers need to discern objects at night.  The two critical road signs at this intersection (left) are difficult to see because the eyes are overwhelmed by direct light, creating a hazard.  Glare hinders true security by creating extreme shadows, offering refuge to criminals in spite of the bright lights.  Glare can be discomforting, disabling, or blinding.  As we age, the effect--and its impact on our lives at night--becomes worse.

 

Aim adjustable lights downward so they are level with the horizon. Purchase dark-sky friendly fixtures that have the light bulb tucked into the luminaire housing, not exposed to the eye.  Install only light fixtures that are fully shielded.  Install security lights with motion detectors for greater security.  With lighted signs, request lighter text and logos/graphics against a dark, opaque background.

 

Light Trespass or Spillover

 

Spillover is light that extends beyond the targeted object.  This includes light trespass, which extends beyond property lines.

 

Light that is broadcast well beyond the intended area is wasted--an unnecessary loss of money.  Light that encroaches upon the property of others, such as into bedroom windows, is a personal infringement.  Neighbors are entitled not to have your bright lights shining into their personal space.  Roadway light that spills into adjacent properties represents a waste of tax dollars.

 

Contain floodlights with clip-on visors and aim the fixtures downward.  Install fully shielded lights, and do not place light mounts where the light crosses property lines.  Save money by lessening the light output (in lumens) of existing fixtures. 

 

Skyglow

 

Sky glow is the garish hue seen overhead from artificial light scattering in the atmosphere. The reflected light masks the background stars and creates a pallid-looking sky.  

 

You could readily save the tax dollars spent on lighting the clouds.  Light sent skyward is a waste of that light (<2% of the cost) plus the additional energy loss (~98% of the cost) that went into producing the light pollution.  (See Energy Chain.)  Our children are losing the heritage of the night sky.  Most of them are unable to see the Milky Way galaxy or other dark sky wonders.  Nocturnal animals are disrupted by the abnormal night lighting.  Some studies suggest human health is negatively affected because of disrupted circadian rhythms due to light pollution.

 

Install simple visors over existing lights and purchase fully shielded fixtures.  Find a less offensive way to express yourself than through outdoor vanity lights (right) and landscape lighting.  Ask your elected officials to select public lighting fixtures that don't waste your tax dollars skyward.  Help reclaim the vast public space overhead.  Aim billboard lights down instead of up.