Ideas for Astronomy Science Fair Projects

by Dr. James Pierce

Emeritus Professor of Astronomy
Minnesota State University, Mankato

The scientific method is based on observation and experimentation. Good science fair projects should be based on these activities as much as possible. Following is a list of astronomy experiments and observations that can be performed with a minimum of equipment. Many will require a few weeks to perform, as astronomical phenomena cannot be rushed. All should result in the generation of data that will provide the experimenter with a clue to the workings of our corner of the universe.

  1. In what direction does the sun rise and set? How does a sundial work? Use shadows to trace the sun's motion. Measure length and direction of the shadow of a standard gnomon (e.g. a vertical pole) and record this data as a function of (a) time and (b) date. This will reveal (a) the sun's diurnal (E-W) motion and (b) its annual (N-S) motion in our skies.

  2. When is the earliest sunset? When is the latest sunrise? When is the longest day? Measure and record the time and direction of sunrise and sunset over several weeks or months and plot the results.

  3. In what direction does the moon rise or set? When is the moon visible in the sky? Measure and record the time and direction of moonrise and moonset over several weeks. Try to predict where and when the moon will rise and set next. Can you predict where the moon will be seen after several cloudy days? What shape will it have?

  4. Can you read by the light of the moon? Devise a method to measure the brightness of the moon (perhaps use a light meter, or measure the distance at which you can read a standard size of print by moonlight) and record its brightness as a function of phase and altitude in the sky.

  5. Why does the moon appear larger at some times? Some claim the moon appears larger when near the horizon. Record the variation in the moon's angular diameter as a function of altitude and phase. You should see variations due to the moon's changing distance from earth. From your data, try to determine when apogee and perigee occurred. Compare with published dates.

  6. How fast does the moon move through the stars? Record the position of the moon with respect to the sun and stars, and from the variation in its orbital rate, try to determine the dates of apogee and perigee. [See Kepler's 2nd Law.]

  7. At what rates and in which directions do the planets move among the stars? Measure and record the positions of visible planets with respect to the stars. From this data, calculate their orbital periods and compare with published data. Watch out for retrograde motion.

  8. How soon after sunset does the sky become dark? Determine the length of twilight at different times of the year by observing the time at which certain bright stars first appear and comparing with the sunset time. (Beware of variations due to the stars' different altitudes. Try using Polaris as a standard.) Also note the time at which automatic streetlights turn on. Determine how soon after sunset stars of different magnitude (brightness) appear.

  9. Which stars appear brightest to you? Devise your own scheme for measuring the brightness of a star (don't use magnitudes). Use it to measure the brightness of a variety of stars, bright and faint, and compare your results with published values. Compare your brightness values with published magnitudes.

  10. Can star colors be measured with black-and-white film? Take pictures of stars, using color film. Note the star colors. Estimate the brightness of each star from your photo by measuring the thickness of the star trail. Compare with published brightness and color. Repeat the process using black-and-white film and try different colored filters over the camera lens. (Be sure to make careful records of what you are doing.) Now estimate the brightness of each star. Are they the same as before? Can you tell the star colors from your black-and-white photos?

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Created February 12, 1999; last modified March 19, 2021
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