July 3, 2008 (9 images)

Updated: July 3, 2008 at 2:29 PM
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NASA announced that recent analysis of data from a January 2008 flyby of the planet Mercury by the Mercury Surface, Space Environment, Geochemistry and Ranging (MESSENGER) spacecraft shows that volcanoes were involved in plains formation and suggest that its magnetic field is actively produced in the planet's core. (UPI Photo/NASA)
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