Pluto is too big to be an asteroid and too small to be a planet, so scientists call it a dwarf planet. It's so far away from the sun that it gets no warmth at all, so it's covered in a thick layer of ice. Readers learn fun facts such as these as they explore the world of our solar system's dwarf planets. Informative diagrams, full-color photographs, and accessible text help readers discover more about Pluto and the other dwarf planets in our solar system.