Valley on Mercury dwarfs the Grand Canyon

Images recently gathered by NASA's Messenger spacecraft have revealed a giant valley on the surface of Mercury. The valley is over 1000 kilometres long, up to 500 kilometres wide, and the faults that comprise its sides are over three kilometres high. It lies partly within the previously known Rembrandt impact crater.  This makes Mercury's valley much larger than Arizona's Grand Canyon. A new study by Dr. Tom Watters from the Smithsonian Institution's National Air And Space Museum has determined that  this huge valley would have been created by a buckling event related to the planet's cooling process.  As Mercury's single, solid outer plate cools, the planet contracts, or shrinks, resulting in a formation such as this valley. This suggests that Mercury is still warm inside, which is contrary to what scientists previously believed.           

Additional Links: 

• Paper in Geophysical Research Letters: Fault-bound valley associated with the Rembrandt basin on Mercury