How to Use Protractors to Measure Angle to the Sun

The sun is a marker for our passage through time and space. Its position in the sky is not only a function of the time of the day and the day of the year, but also depends on how far north or south of the equator the viewer is positioned. The elevation angle describes the position of the sun and is obtained by measuring the angle between the horizon of the earth and the sun. The elevation angle is largest when the sun is directly overhead, and smallest at sunrise or sunset.

Things You'll Need

  • Needle
  • Protractor
  • String
  • Washer
  • Straw
  • Tape
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Instructions

    • 1

      Make a small hole in the center point of a protractor using the point of a needle.

    • 2

      Pass a piece of light-weight string, 12 inches long, through the hole and tie the string to keep it in place. Attach a washer to the free end of the string and ensure that the weighted string hangs vertically.

    • 3

      Tape a drinking straw to the protractor so that it aligns with the line that joins the 0 and 180 degree points on the protractor.

    • 4

      Hold the device so that the 0 to 90 degree quadrant of the protractor is closest to you and the curved edge of the protractor is pointed towards the ground. Point the straw towards the sun. Do not look directly at the sun.

    • 5

      Hold a piece of paper behind the device. Move the straw slowly until it forms an image on the paper that comprises a dark, circular shadow with a bright spot of light in the center. Hold the device steady once this image forms. Be careful to allow the string to swing freely until it comes to rest.

    • 6

      Pinch the string gently between your thumb and the protractor at the point where the string passes over the curved scale of the protractor.

    • 7

      Read the scale where the string passes over the degree markings. Subtract this angle from 90 to obtain the angle of elevation of the sun with respect to the earth's surface.

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