This is a true scale eclipse model, with both sizes of Earth and Moon as well as distance between them to scale.
[This activity is adapted from the NASA Night Sky Network Shadows and Silhouettes
astronomy outreach kit, developed by Astronomical Society of the Pacific
Materials & Preparation:
- 1 ball - 1" diameter (Earth)
- 1 ball - 1/4" diameter (Moon)
- 1 meter stick or yardstick
- 2 sticks (popsicle sticks, chopsticks, etc) - attach Moon ball to one stick and Moon ball to the other stick.
- 2 paper clamps - use these to attach the Earth and Moon ball/sticks to the meter stick.
- Light (Sun or bright light bulb as model Sun)
What To Do:
Before attaching the Earth and Moon ball/sticks to the meter stick, it's interesting to
- Show only the Earth ball on it's stick and ask "If the Earth were this size, how big would the Moon be? Is it half as big? 1/8 as big? [Correct answer is that Moon is about one quarter the Earth in diameter.]
- Show the Moon ball on it's stick and ask "at this scale how far apart should the Earth and Moon be? [correct answer is about 31" (79 cm) — the Moon is about 30 Earth diameters away from the Earth.]
Attach the Earth and Moon to the meter stick at the right distance.
Using sunlight or bright bulb, have people try to create a "true scale"
- eclipse of the Sun where the shadow of the Moon falls on the Earth, and
- eclipse of the Moon where the shadow of the Earth falls on the Moon.
Both are somewhat difficult. Which is more difficult?