Why does Earth spin?

the long version

"How big is Earth? What is the hottest place on Earth? Why is the sky blue? What is Earth made of? Find out the answers to these and other fascinating questions about Earth. Good Question! books explore what you really want to know about science and nature"--Back cover. Text in question-and-answer format provides a simple overview of planet Earth, its size, how the ground moves under our feet, what we would find if we dug down all the way to Earth's core, why the sky is blue, and more.