Mysterious "Spider Scar" on Mercury Revealed for the First Time

NASA's probe MESSENGER flew by Mercury a couple of weeks ago, and the photos have started pouring in. This is one of the most striking. Nicknamed "the spider," it's probably the result of a meteor impact with about fifty cracks radiating outward from it. Apparently, it's the only such structure in the solar system,… » 1/31/08 7:00am 1/31/08 7:00am