Our Nearest Neighbor: The Moon Children’s Ideas About the Moon

Below are common ideas children in grades K-6 have about this topic, compiled from research on children’s ideas about science (see the Session 1 Children’s Ideas Bibliography). Consider what evidence might refute this idea, and why a child would be likely to believe this?

1. The Moon is much like the Earth.

Young children base knowledge primarily on experience. All of children’s experiences are limited to the Earth, so when they think about the Moon and other planets, their perception is restricted. The Moon is similar to Earth in some ways, but is mostly quite different. Unlike the Earth, the Moon has little or no iron core. Its mass is 1/100th the mass of the Earth, with one consequence being that the Moon cannot hold an atmosphere onto its surface. The Moon is made of rock material that is similar to that which makes up Earth’s mantle, the Moon is not tectonically active.

2. The Earth, Sun, and Moon are all about the same size, or are about half or double of each other’s diameters.

The Moon’s diameter is roughly one-quarter of Earth’s diameter. Although the Sun and the Moon appear to be approximately the same size in the sky, the Moon is actually about 400 times smaller in diameter than the Sun. It is the similarity of the apparent sizes of the Moon and Sun to the naked eye that contributes to the belief that the Earth, Moon, and Sun are all close in size.

3. Students think the Sun and Moon are much closer to the Earth than they actually are.

Large numbers and vast distances are hard for everyone to comprehend, especially children. The apparent sizes of the Moon and the Sun can easily mislead children when they think about the distances between the Earth and these two solar bodies. The Moon is about 30 Earth diameters away from the Earth. The Sun is almost 12,000 Earth diameters away from Earth.

4. There is no gravity on the Moon.

Anything with mass has gravity. Compared to the Earth, the Moon has much less gravity because it is made up of, for the most part, light materials and has a relatively low mass. The moon attracts objects at its surface with 1/6 the force of Earth’s. Textbooks often mention that Earth’s gravitational force holds the atmosphere to it. The knowledge that the Moon has no atmosphere can contribute to children’s confusion about the Moon’s gravity.

5. There is no gravity in space.

There is no place in the universe that has no gravity. Everything that has mass in the universe is exerting gravitational force. If there were no gravity in space, then moons would not orbit planets, and planets would not orbit stars. The common conception that air is necessary for gravity can mislead children to believe that there is no gravity in space. This belief can persist through high school.