The outer planets, which are Jupiter, Saturn, Neptune, Uranus are truly fascinating not only because of their size, but also because they offer some of the most unusual worlds we have ever seen. Readers will be intrigued with the scientific details of each planet, which follow the Next Generation Science Standards focusing on the solar system, including their size, temperature, and pressure of their atmospheres, their weather, and their interiors. Readers will also learn about each planet's moons, which are unique worlds unto themselves and which may offer our best chance for finding extraterrestrial life.