Our closest solar system is about 10 light years away. It has two main types of planets. Some are rocky and small, like planet Earth, while others are huge balls of gas, like Jupiter. Astronomers once thought our solar system was the one and only. But now we know of hundreds of solar systems. One may even have a planet like Earth! Just maybe, these alien worlds could host life, like our own amazing planet. This book allows students to use observations of the Sun, Moon, and stars to describe patterns that can be predicted.