* Astronomy

A mysterious circular pattern on moss-covered logs has scientists scratching their heads.
Last winter, researchers in the Great Smoky Mountains National Park discovered the symmetrical bull's-eye pattern on patches of liverwort (a close relative of moss) growing on pine trees that had died and fallen on the ground.
At this point, biologists aren't sure what causes the circles. Some have suggested snails, while others have speculated millipedes.
Etched into the velvet-green surface of the liverwort, the patterns have appeared like tiny crop circles. The only reports of anything similar come from the arctic regions of Greenland and Canada, where a moss-eating fungus is believed to be the cause.

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