Science project

Counting Sunspots

Research Question:

  • Can you use the data you collect to figure out how fast the sun rotates?

The sun has periods of increased solar maximum and decreased solar minimum sunspot activity. The sun journeys through an 11-year cycle. Before you begin this project, research the sunspot cycle and determine where we currently are in the cycle.

Safety Note: Never look directly at the sun. Doing so could damage your eyes.


  • A piece of cardboard
  • Scissors
  • Ruler
  • Aluminum foil
  • Sharp pin or needle
  • Paper
  • Pen or pencil
  • Lab notebook

Experimental Procedure:

  1. Construct a pinhole projector by doing the following: Cut a square hole (2-3 cm across) in the center of a piece of cardboard. Tape a piece of aluminum foil over the hole. Use a sharp pin or needle to poke a hole into the center of the aluminum foil.
  2. Use the pinhole projector you've just made to project an image of the sun onto a piece of paper. Do you notice any dark spots on the image that is projected? Trace them.
  3. Repeat the above step on a fresh piece of paper every day for two weeks (ideally around the same time of day).
  4. Analyze the data you've collected. How does the pattern of spots change over the course of the two weeks? Could you use this information to determine how fast the sun rotates? Record all of your thoughts and observations in your notebook.

Terms/Concepts: rotation of the sun; sunspot cycle; solar minimum sunspot activity; solar maximum sunspot activity


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Warning is hereby given that not all Project Ideas are appropriate for all individuals or in all circumstances. Implementation of any Science Project Idea should be undertaken only in appropriate settings and with appropriate parental or other supervision. Reading and following the safety precautions of all materials used in a project is the sole responsibility of each individual. For further information, consult your state's handbook of Science Safety.

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