On an interesting note, Mercury's period of rotation may have been much faster than it is now. At one time in its past, it rotation could be as rapid as eight hours, however, due to its near proximity to the Sun, solar winds slowly despun the rapid rotation to the current 59 some days. Calculations on this matter show that the process would take around 109 years while raising Mercury's interior temperature by 100 degrees Kelvin.
Slow Despinning 
