The Moon
The moon is in the sky. You can see it at night. Some days you can see it in the day too.
The moon does not make its own light. The sun shines on it. That is why it looks bright.
The moon looks like it changes shape. One night it is round. A few nights later, it looks like a thin bow. The moon is not really changing. We just see a different part of it that the sun is lighting up.
People have been to the moon. They hopped and left boot prints in the dust.