Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to ...

The boundary between the two lies about 465 miles (750 kilometers) beneath the Earth's surface. The crust is the outermost layer of the Earth. It is the familiar landscape on which we live ...

With a radius of 3,959 miles, Earth is the fifth largest planet in our solar system, and it's the only one known for sure to have liquid water on its surface. Earth is also unique in terms of ...