What's the difference between an asteroid and a planet? Scientists struggled with this question for many years with regard to Ceres. Today, it's called a "dwarf planet" and because of the Dawn Probe, we know a lot about it! Robots have many cool features that bring the far reaches of space to scientists on Earth, and readers learn about the amazing technology the Dawn Probe used to explore Ceres. Up-close photographs and full-color illustrations complement...