Tracking the Sun with a Solar Dome

Activity:
Measuring the daily and annual path of the sun through the sky on a model of the celestial sphere.

Science Standards:
Patterns of Change, Scientific Models (Conceptual)

Objectives:

  • The student will safely and systematically observe the Sun's path.
  • The student will understand the daily motion of the Sun.
  • The student will create a conceptual model of the celestial sphere.
  • Materials:

  • magnetic compass (for the teacher)
  • 2 liter soda bottle (one per student)
  • scissors
  • permanent marking pen
  • cellophane tape
  • ruler
  • construction paper or cardboard sheets
  • chalk


  • Introduction:
    The sky is often modeled as a transparent hemisphere. The path of the Sun across the southern portion of the sky makes an enormous arc. This arc changes altitude with the seasons being a high arc in the summer and low arc in the winter. The large arc results in long summer days and warm temperatures. Conversely, the lower winter arc results in short winter days with cold temperatures and long shadows.

    Directions:
    1. Construct the Solar Dome. Using a sheet of cardboard, index paper, or construction paper, draw lines perpendicular to the sides to mark the center of the sheet as shown. Cut a hemisphere from the the bottom of a two liter bottle and center over the "x" marked. Secure with tape.

    Solar Dome
    2. Outside alignment of Solar Dome. Using a compass , align the lines drawn on the sheet with the cardinal directions. Carefully "chalk" the outline of the sheet so that it can be returned to its exact alignment.

    3. Marking on the Solar Dome (repeated measures). Using a permanent marker, hold the pen near the surface of the dome such the the shadow of the tip is on the crossed lines at the center of the sheet. AT NO TIME SHOULD THE STUDENT LOOK AT THE SUN!! Mark on the dome in this manner about once each hour for an entire day. Connect the lines to form the arc of the Sun's path. This project should be repeated several months later to demonstrate how the Sun's path changes.