Mercury is the closest planet to the Sun. Because of this, scientists are not able to point telescopes toward it, making Mercury particularly difficult to study. However, new missions to Mercury are planned over the next seven years, which are expected to reveal information about the planet’s geology, density, core, composition, and magnetic field. This book provides descriptions of these future missions as well as the most current information available today. This revision of Mercury includes the most up-to-date information on and about the planet. References no longer refer to Pluto as a planet. Also includes timeline and updated back matter.