Mercury's Speedy Spin Hints at Planet's Insides

Mercury is a spinning faster than scientists had thought: New research shows that the planet completes a rotation on its axis roughly 9 seconds more quickly than scientists previously charted — and that data will help scientists understand more about the planet's molten core. Based on the data collected from NASA's MESSENGER spacecraft, scientists think most of Mercury contains a molten core that takes up 70 percent of the planet's mass. "One possible explanation for Mercury's faster