New evidence suggests large asteroid strike may have influenced Mercury's spin
Monday, December 12, 2011 - 09:30
in Astronomy & Space
(PhysOrg.com) -- Planets orbiting a sun generally, but not always spin on their axis. Some spin east to west, others west to east. Those that don’t spin are said to be tidal locked with their sun; always showing it the same face, such as the moon does with planet Earth. In these instances, the planet tends to develop different properties than it would were it spinning. One side is cold, the other hot, for example leading to unique geophysical properties. Also because of the sun’s gravitational pull, more asteroids are likely to hit the far side of the planet, leaving more craters.