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Table of Contents

How Many Stars?

Who should participate?

This important, and fairly easy to perform Star Count project is designed as part of an international scientific study to investigate the visual quality of the nighttime sky and to help assess the national and global extent of atmospheric light pollution. It will also help to evaluate the amount of energy wasted through poor or inappropriate lighting practices.

Teachers, students, youth organizations ( e.g. Cubs, Scouts, Guides etc.) amateur astronomers, science and environmental organizations, and dedicated interested individuals, are all invited to participate.

Why Should You Participate?

The number of stars that one can see in a cloudless, moonless sky at night depends critially upon two factors,

  1. The condition of the atmosphere (water vapour, dust and pollutants - both particles and aerosols - which combine to form smog).

  2. The amount of backscattered artifical light (from upward shining sources).

Wasted energy (from poor lighting practices) and air pollution (from environmentally "unfriendly" sources) conspire to deplete the nighttime sky of visible stars.

By partciplating in this star count activity you will be helping to identifiy the national and global extent of atmospheric smog and haze. It will also assist in obtaining an estimate of the amount of energy wasted through poor lighting practices.

Teacher's Notes

The Star Count Project is designed to facilitate the teaching of specific curriculum outcomes/expectations for grades K thought 12 and are linked to the outcomes in the Pan-Canadian Science Curriculum.

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Critical Information

To undertake this project there are a few pieces of critical information that you will need to provide.

These are

  1. The longitude and latitude of the location at which you will make your observations.
    Latitude and Longitude

  2. A valid e-mail address (which will only be used for registration purposes).

  3. The time and date of your observations and pollution index.

  4. The calculated result derived from your observations.

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Observation Protocol

  1. Select a moonless night after the end of astronomical twilight.
    Darkness [details]

  2. Allow your eyes to become "dark adapted" for at least 20 minutes before beginning
    you star count.
    Dark Adaptation [details]
    Do not allow your eyes to lose their dark adaption until the experiment is completed.

  3. Select a clear and cloudless sky on an night which is as free from haze and smog as possible.
    Sky Conditions [details]

  4. If possible, select a site that has a low horizon as unobstructed by buildings and trees as you.
    Horizon [details]

  5. Avoid a location which is in direct view of bright lights.
    Local Illumination [details]

  6. Evaluation and Test Results [details]


Prepared by YES I Can! Science Team at McMaster University,
for the Canadian Space Agency.