What is the surface of Mars like? Why does Venus glow in the dark? How do scientists explore faraway planets? In this book, you'll find out the answers and lots more fascinating facts about the Solar System. The Solar System is part of an exciting series of book with easy reading text. The Earth is a planet. It's a huge, round lump of rock floating in space. The Earth is one of eight planets that travel around the Sun. The Sun and the planets are called the Solar System.