Space explorers are people who study objects in space and advance human knowledge. Since ancient times, people have been studying the sky, tracking the movement of celestial bodies, and developing theories to explain what they observed.

Includes index.

What is a space explorer? -- Exploration vehicles -- Galileo -- Carl Sagan -- Yuri Gagarin -- Neil Armstrong -- John Young -- Valentina Tereshkova -- Unmanned exploration -- Making the grade -- The space shuttle -- The future of space exploration -- Test your knowledge.