Light Pollution of the Night Sky

Objective:

• The objective of this project is to study and understand the effects of light pollution.

Materials:

• Teams of students to participate and transportation, flashlight, star gazing map, a journal of some sort to record a form to record your data (one is included on this page for your convenience), a flashlight with red cellophane (red light is better for night vision) over the lens.

Procedure:

• Be aware of which star gazing map provided on the page is appropriate for you to use. If you are participating in the project during September, October, November, or December you will be looking for the Great Square. If you are participating in the project in Janruary, February, March, or April, you will be looking for Gemini. If you want to set up a program during the summer, contact EMAIL Bill at

• Working in teams of three, pick a location that is located within a central area of your town. This area should be well lit with artifical light after dark. If you are working on the great square, go to this location, between 9pm and 10pm, if it is August or September, between 8pm and 9pm if it is October, between 7pm and 8pm if it is November and between 6pm and 7pm if it is December. If you are working on Gemini, go to this area between 8pm and 9pm if it is January, or 7pm and 8pm in February, March, April or May. Upon arriving, each member should expose your eyes to some light source. You can do this be simply studying your star gazing map with a car dome light or your flashlight with the cover off. Once you have done this, find the constellation that is appropriate for the time of year you are participating.

• Next, each member should count the number of stars visibe including the border of the constellation you are working on and the stars within that border. Average your three outcomes and use that number as your result. We have provided the following form for you to record your data.

      DATA FORM FOR LIGHT POLLUTION OBSERVATIONS

CITY      _______________
STATE     _______________
OBSERVERS ______________________________________________

CONSTELLATION  _______________________

                     STARS SEEN AFTER [ ] MINUTES
SITE  DISTANCE   0min    5min   10min   15min     20min
 1    ____       ____    ____   _____   _____     _____
 2    ____       ____    ____   _____   _____     _____
 3    ____       ____    ____   _____   _____     _____
 4    ____       ____    ____   _____   _____     _____
 5    ____       ____    ____   _____   _____     _____



This data can be plotted in two ways:

Plot the total number of stars in each column vs the time.  This
gives a measure of light adaption of our eyes.

Plot the number of stars in the '20 minute' column vs the distance. 
This gives you an idea of the light polluting effect of your city
or town.




• At five successive five minutes intervals, repeat this procedure without exposing your eyes to any light source. You should notice an improvement in your night vision as your eyes accomodate for the darkness. Record your data each time.

• Next, you will move to designated areas outside of this well lit area spaced 5 to 10 miles apart. Your spacing will be determined by the size of the city you are working on. In Las Angeles , for example, your spacing might be from 10 to 30 miles apart. You will repeat the procedure at each of these areas. The areas should be spaced approximately five miles apart, moving away from the well lit area.

Questions To Consider

• What kinds of conclusions can you draw from you results?
• Could you correlate your results to a mathmatical equation?
• How do your findings vary among cities?
• Why do you see more stars as you sit in the dark longer?
• How do your findings vary within your team?
• Why was it benifical to work in teams of three and average your results?

We are eager to hear from you. Please contact: Libby@astro.wnmu.edu with your results.

For a more in depth introduction to light pollution, check out the International Dark Sky Association.