To understand what causes light pollution and how it can be curtailed.
This lesson provides a context in which students can consider and discuss some of the benefits and drawbacks of technology, as it relates to light pollution.
In this lesson, students will consider the negative consequences of nighttime lighting, enabled by the invention of electric lights at the close of the 19th Century. They will discover that there are unintended consequences resulting from our ability to illuminate the night, just as there are benefits.
In particular, they will learn how excessive night lighting in suburbs and in rural areas from street lamps and other sources of "light pollution" have obscured our view of constellations, meteor showers, and even the planets. This has had an impact not only on our enjoyment of the night sky, but also on the science of astronomy which relies on observations of extremely faint objects that can be made only with large telescopes at sites free of air pollution and urban sky glow.
The long-term interests of society are best served when key issues concerning proposals to introduce or curtail technology are addressed before final decisions are made. Students should learn how to ask important questions about the immediate and long-range impacts that technological innovations and the elimination of existing technologies are likely to have.
Teachers can help students acquire informed attitudes on the various technologies and their social, cultural, economic, and ecological consequences. When teachers do express their personal views (to demonstrate that adults can have well-informed opinions), they should also acknowledge alternative views and fairly state the evidence, logic, and values that lead other people to have those views. (Benchmarks for Science Literacy, p. 335.)
Refer to The night sky in the World for background information on light pollution.
In addition, preview the following images of the earth at night (these can be shown to the class to help students visualize the concepts covered in this lesson). Upload the highest resolution images that you can from these pages, as the higher the resolution is, the clearer the image will be:
To enrich their understanding of how technology has shaped how people live now, students should examine what life was like under different technological circumstances in the past. They should become aware that significant changes occurred in the lives of people when technology provided more and better food, control of sewage, heat and light for homes, and rapid transportation.
To help students develop this understanding, discuss with the class what the night sky looks like today and contrast it to what it might have looked like 100 years ago. Then, ask students if they have heard of light pollution, and what they suppose that it might be.
Have students view the images of night on earth as seen from space. (See the Planning Ahead section for image sources.) These images clearly show that the more industrialized countries are also the most illuminated.
Show students the Outdoor Lighting Ordinance for Boulder, Colorado. Have the class look at the photographs of shielded and unshielded night light in the middle of this page. Ask if students can see the difference between shielded and unshielded lighting.
Now students should use their Too Bright at Night? student esheet to read these articles:
Then discuss student answers to these questions from the Too Bright at Night? student sheet:
- What are some of the reasons that the night sky is “brightening?”
(Industrialization, electric lights in homes and businesses.)
- Is all of this brightening necessary?
(Answers may vary. However, students should mention that many experts believe that most sky glow is unnecessary because it is the result of inefficient lighting.)
- What problems are caused by excessive lighting of the night sky?
(It makes it difficult to see heavenly bodies with the naked eye, it is more difficult for telescopes to view celestial objects from earth, there is a loss of habitat for nocturnal animals, a disruption of migration patterns for birds, and so on.)
- Who or what is being affected? What are some of the problems for animals?
(In astronomy, ground telescopes are losing effectiveness; for humans, excessive light may decrease melatonin production; sea turtles get lost searching for beaches to lay eggs, noctural animals abandon habitats; people who live in developed areas have obscured view of constellations, meteor showers, and even the planets.)
- Can anything be done about it?
(We could curtail use of globe lighting, use light fixtures that use motion sensors or that contain and/or direct light downward, timer controlled lighting, and glare free lighting are possible solutions.)
- Will everyone want to reduce the brightness of the night sky? Why, why not?
(Answers will vary.)
- How would reducing light pollution save money?
(Using timers and motion sensors would cut down on wasted energy, which would save money. Bulbs would last longer.)
- Is there a solution that would still enable us to provide nighttime illumination for those who need it?
(Use lights that reduce glare where constant nighttime illumination is necessary, use devices like sensors or timers in order to provide illumination only when it is needed.)
Your job is not to provide students with the "right" answers about technology but to see to it that students know what questions to ask. Therefore, conclude the lesson by asking students to brainstorm a list of questions that they might ask if they were responsible for deciding whether or not to pass an ordinance in their town to reduce the brightness of the night sky.
Using Part 2 of the Too Bright at Night? student sheet, have students list the rewards and risks of the technology that is causing sky pollution.
Students are then directed to write a brief statement outlining what, if anything, they think should be done about light pollution. Their statement should include specific references to actual problems and descriptions of any remedies that they think might be effective.
Students can do an assessment of the level of light pollution in their community overall and in their neighborhoods. They can find examples of wasteful nighttime lighting and propose remedies for the problem.
Hawaiian Astronomical Society’s page Why You Can't See the Stars contains links to other resources on light pollution.