If you are out in the countryside or at sea and you look back over a town or city you will see a glow (usually orange from the street lights) over the area - this is called light pollution. Light being shed skywards from lampposts and other lights in cities and towns causes all the faint stars disappear, leavng only the Moon and the brightest planets and stars visible.
To reduce light pollution, instead of letting all the light escape upwards where it is no use to anyone, we must design lights that stop spillage from the top and sides and instead point the lights downwards where it is useful.
In this activity you will build a DIY planetarium in your classroom, and allow your students to explore the effects of light pollution, experiment with possible solutions and learn why astronomers need dark skies.
Dark Skies and Light Pollution Teacher Guide
Dark Skies and Light Pollution Student Worksheet
Full Instructions
Learning Objectives
- Explore the effects of light pollution and experiment with possible solutions.
- Discuss the best location to build an observatory or carry out astronomical observations.
Materials
- Printed Dark Skies and Light Pollution Student Worksheet per student
- Printed LCOGT observing sites or Observatory Images Powerpoint
- Small cardboard box (7cm x 7cm)
- Paper plate (white) or white paper
- Large blanket or two
- Flash Light x2
- Illustrated book
- Figurine
- Tape
- Pin
Step-by-Step
Preparation
Before beginning the activity, create a DIY planetarium in your classroom by following the steps below:
1) Drape the blanket over a decent sized desk and ensure you block out all light. This is your DIY planetarium.
2) Stand an open book on the floor inside the DIY planetarium with a detailed illustration visible and stand the small figurine within the book.
3) Take the cardboard box and poke holes in the top using your pin. Create a distinctive shape (e.g. an alien, a smiley face, a common constellation). The holes will act as the stars in our night sky.
4) Place a flash light inside the box so its light shines through the holes. Use tape to hold the flash light in place.
5) Finally, place both box and flash light inside your DIY planetarium so that the light from the flash light shines through the holes and onto the underside of the table.
Activity Steps
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Divide the students into pairs. Ask them to enter the DIY planetarium one pair at a time. Before they enter, provide each pair with a flash light, a small paper plate and a Dark Skies and Light Pollution Student Worksheet.
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When each pair has entered the DIY planetarium and have discussed in pairs the points listed on their worksheets, lead a group discussion around the following points:
- Does the lampshade make it easier to see the landscape (the image in the book)?
- When are the stars more visible?
- When is the figure more visible?
- If the flash light was a real lamppost, would it be more suitable in the streets for people walking at night?
- What affect do lampposts have on astronomical observations in towns and cities? How could this be fixed?
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Based on this activity, where is the best place to build an observatory? (E.g. in a busy city, in the countryside, on a mountain.)
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Show the students the photos of the LCOGT observing sites or using the Observatory Images Powerpoint, and discuss why these sites may have been chosen:
- The observing sites are remote; far from light pollution.
- Some are located in dry, desert landscapes without much rain or cloud cover.
- All are high altitude to sit above cloud cover, rainstorms etc.
- No lampposts or public lighting at observing sites.
Conclusion
Now that the students understand the benefits of a dark sky observing location, use the robotic telescopes to show just how impressive a good view of the night sky can be. Choose any object from the list provided on the observing website.
You can also use LCOGT’s All Sky Cameras to enjoy a fantastic view of the night sky by visiting lcogt.net/camera/