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Live From...the Hubble Space Telescope
Star Census Classroom Collaboratory

Activity Sheet

stars in space

Try this experiment to measure the number of stars you can see.

1. Make an "Observing Device" from a bathroom tissue or paper towel tube. Measure the diameter of your tube. Cut its length to be three times its diameter. Through the tube, you will see only a small portion of the sky. It would take 144 tubes to cover the whole sky.

2. One by one, face in each of the 4 compass directions (North, South, East and West).

3. Hold the tube 3/4 of the way up from the horizon in each direction and count the number of stars seen through the tube. Hold the tube half-way up from the horizon and repeat the count. Repeat the procedure again with the tube pointed a third of the way up. Repeat observations for the other directions. Record your data below.

Area 3/4 up 1/2 up 1/3 up Total
North ...... ...... ...... ......
South ...... ...... ...... ......
East ...... ...... ...... ......
West ...... ...... ...... ......
Total ...... ...... ...... ......
Grand Total ..........

4. Add up the number of stars for all 12 sightings. If it takes 144 tubes to cover the sky, then you have observed 1/12th of the sky. Multiply your sub-total by 12 to estimate the total number of stars in the sky. Estimated total number of stars:_________ (includes the stars above and below the horizon)

5. Add up and compare the three measurements in each direction. Why do you see more stars in certain directions?



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