Do you know which planet is the smallest in the solar system? It's Mercury! Despite only being slightly larger than Earth's moon, Mercury is a fascinating planet with a large role to play in the solar system. This engaging volume explores Mercury's features, such as its extreme temperatures and cratered surfaces. The friendly, informative text, vibrant photographs, and illustrations make learning about this planet a fun adventure. Fun facts--such as that Mercury's day lasts longer than its year--and accompanying visual tools such as graphic organizers equip readers with knowledge to expand their understanding of space science.