Day into Night

DIN Unit 3: Light Pollution

Introduction :: Activity 1 :: Activity 2

Activity 1: Northern Hemisphere, late summer or early fall

Objective

In this activity, students will be introduced to the factors that influence light pollution by observing the constellation Cygnus.

Materials

• Recording Forms 1-4
• Pencil
• Flashlight which has been prepared for nighttime use
• Star chart

Several websites have star maps that you can download. They include:

• www.skymaps.com
• www.gsat.edu.au/astronet

Vocabulary

• Cygnus
• Stellar magnitude

Procedure

1. Review the procedures for a nighttime field trip and pass out permission slips.
2. Arrange for several parents to take calls in case of bad weather.
3. Begin at least one hour after sun set. Once you gather the students at your observation place wait at least 15 minutes to allow your eyes and theirs time to adjust. While you are waiting, discuss any sources of light pollution and have your students write them in their journals.
4. Instruct students to locate Cygnus (using their star charts). Starting with Recording Form one, have the students circle every star on the form that they can see in Cygnus.
5. If they see more stars than those on Recording Form One, have them go on to form 2. Have them circle every star they can see on Recording Form two. Continue through the forms in this manner. Only locations with very little light pollution will be able to see stars on chart four.
6. Have the students staple their charts and their report forms into their journals.

Discussion

Students should bring their Recording Forms to class the day following your observation and discuss their answers.

Conclusions

Students should use their collective data to draw a conclusion regarding light pollution at your location.

Appendix: How to prepare for nighttime observation

Observe at least one hour after sunset to eliminate the effects of sunlight

Wait 10–15 minutes before observing to allow their eyes time to adjust to the dark. While the students are waiting they can look for artificial sources of light pollution such as street lights, or security lights.

Prepare your flashlight for nighttime use. The human eye needs to adjust to the dark before it can observe properly. Using a normal flashlight to help one record what they see in the sky would ruin any adjusting that the eye has done. Hence, a flashlight has to be specially prepared before it can be used while observing. To do this, place several layers of red cellophane or two coats of red fingernail polish over the flashlight. The color red does not disturb night vision as much as normal (white) light does.

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