Mercury's magnetic field is about 100 times weaker than that of the Earth - a curiosity that scientists have been trying to make sense of for years.

Recent observations of Mercury's rotation suggest that the planet has a partially molten core, and scientists at the University of Illinois and Case Western Reserve University developed laboratory experiments to model what might be happening beneath the surface.

Some residents of Reno, Nevada, are leaving their homes after two months of scattered earthquakes. An earthquake that registered 4.7 on the Richter Scale hit Friday night - the strongest in a string of shakes that started way back at the end of February. But that wasn't all: More than 150 aftershocks rumbled through the region over the weekend.

No, you can't hike or spelunk or even tunnel down to the center of the Earth, even if movies like The Core or this summer's 3D adventure flick, Journey to the Center of the Earth, suggest otherwise. To find out about our planet's insides, scientists rely on very different tricks. And, apparently, a little luck.