Light Pollution of the Night Sky
- The objective of this project is to study
and understand the effects of light pollution.
- 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.
- 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
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
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
- 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
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