Much of what we know about the cosmos has been learned from space probes. For over 50 years, scientists have been sending unmanned machines throughout the solar system. Space probes have been to Mercury, the planet closest to the sun and they have landed on passing asteroids. Two have even journeyed past the edge of our solar system and are still going. Readers are introduced to many of these space probes and learn what the probes have discovered. Remarkable photographs of space probes and their destinations are sure to enthrall readers at any level.