Long ago, people observed comets, asteroids and meteorites with wonder and fear. What were these unusual rocks that dropped from the sky, strange lights that flashed and glowed, and craters that dented the ground? Today scientists continue their quest to learn more about these amazing -- and sometimes dangerous -- space rocks. The sixth book in the popular Starting with Space series features NASA photos of these space phenomena, including close-up glimpses from space probes such as Galileo.