Planets - All Aboard Science Reader, Level 2 Author:Jennifer Dussling, Denise Ortakales (Illustrator) Where does the word "planet" come from? How long is a year on Mercury? What is the temperature on Venus? Is Pluto really a planet? This new Level 2 All Aboard Reading book will answer these questions and more about the solar system. The information is a perfect introduction for young skywatchers.