What goes up must come down. Everybody knows that. But what is it that pulls everything from rocks to rockets toward the center of the earth? It's gravity. Nobody can say exactly what it is, but gravity is there, pulling on everything, all the time. With the help of an adventurous scientist and his fun-loving dog, you can read and find out about this mysterious force.
The sun brings heat, warmth, and energy to the Earth. What is the sun made of? How big is it? How far away? Read and find out!