Within our solar system are four rocky planets. We have named them the inner planets because they are closest to the sun. But what do we know about these rocky places? The Inner Planets explores Earth and its nearest neighbors and uncovers the space science and space missions that have helped us learn about these rocky worlds. Science-filled explanatory text reveals what and how we have learned about the inner planets, the history of this space science, and what the future holds. Detailed sidebars set out fascinating facts about the rocky planets.