With the MESSENGER probe set to crash into Mercury this month, it’s nice to look back on some of the finest data that it gathered during its tenure orbiting the smallest planet of the solar system. The image shows the Caloris Basin, the largest impact basin on Mercury and one of the largest in the solar system.  The result of a massive asteroid impact during the early days of the solar system, the 1,500 Km wide crater was filled with lava aeons ago when Mercury was geologically active (seen in orange).  Large impacts have punctured the surface of the basin since...