8A10.25-Phases of the Moon

8a1025 8a1025b

Videos: Institute of Physics Demo

Description: Students are able to observe the phenomena that creates the phases of the moon using golf balls.


  • Light source for sun (NOTE: SEE BELOW for specific sun setup for each room!)
  • Enough golf balls for the students in the class.

For Rooms 126/124/134:

  • 200 W light on a base
  • Variac to power light

For Room 20:

  • Wooden table
  • Three, 300 W halogen spotlights.
  • Power strip to plug lights into.
  • Three table clamps.
  • Three medium-length poles.
  • Three s-clamps.

Setup Procedure:

For rooms 124/126/134:

  1. Plug in Variac to table and to light source.
  2. Leave box of golf balls near door for students to pick up.

For room 20:

  1. Mount spotlights as close together as possible, as high as possible, on the table.
  2. Plug all the lights into the power strip.
  3. Make sure the lights shine on ALL seats in the room, with as little overlap as possible
  4. Leave box of golf balls near door for students to pick up.

Demonstration Procedure:

  1. Turn off main room lights.
  2. Turn on “sun” light source.
  3. The students’ heads are the Earth, and the golf ball is the moon.
  4. Have the students move the golf ball around their head to different positions to see the different moon phases.