This activity helps children understand the relative sizes of the Sun, Earth, and Moon, as well as their relative distances from each other.
Sometimes, when you look up in the sky, the Sun and the Moon can appear to be the same size. That’s because the Sun is nearly 400 times farther away from us than the Moon! In reality, the Sun is actually 400 times larger than the Moon.
To help you understand the relative sizes of the Earth, Moon, and Sun, go outside with the three objects. Have one person hold the beach ball, which represents the Sun. A second person holds the ping pong ball, which represents the Earth, and counts out 400 steps. Then a third person stands one step away from the ping pong ball with the marble, which represents the Moon, standing between the other two people. (Note: These are just approximations. The Sun is actually more than 100 times bigger than the Earth!)
How much larger does the beach ball appear than the ping pong ball when it’s farther away? Can you block the beach ball by holding up the marble to your eye? What happens when you move farther away?