When is a planet not a planet? Dwarf planets orbit the sun, are solid bodies, and are not moons. But they are not considered regular planets. Learn more about these spherical oddities and why Pluto is still hotly debated today.

With Earth suffering from out-of-control climate change, fourteen-year-old twins Lila and Max Hartfield are facing a dangerous six-month trip to the Mars colony, where their scientist parents have been for the last six years--but on the last day something goes seriously wrong.

"Describes the dwarf planet Pluto and the 2006 decision to change its status from a regular planet"-- Provided by publisher.