With a rotational period of 59 days, this body was the subject of the Mariner 10 mission and sees the largest temperature variation in the solar system.
Among the features of this body are the Caloris Basin, and the Borealis Quadrangle contains its Goethe Basin. At one point, this body was the subject of some confusion which led to the eventual discovery of the star 31 Crateris. A mission hoping to learn about its magnetic field is being launched by the European Space Agency and titled BepiColombo. Examination of this body have led to an unstable outer layer known as an "exosphere" and researchers using a VLA in 1991 found evidence to support the existence of thin ice caps. With a rotational period of 59 days, this body was the subject of the Mariner 10 mission and sees the largest temperature variation in the solar system. FTP, identify this planet that was the subject of the appropriately named MESSENGER spacecraft, the closest planet to the sun. 
Among the features of this body are the Caloris Basin, and the Borealis Quadrangle contains its Goethe Basin.
Mercury 