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          This picture was  nominated as a  featured picture candidate in April 2006 and  July 2007. | 
         
        
        
        
        
       
        Summary 
        One of the most perfect spheres ever created by humans. A fused quartz gyroscope for the Gravity Probe B experiment which differs from a perfect sphere by no more than a mere 40 atoms of thickness as it refracts the image of  Albert Einstein in the background.
         Licensing 
        
         
          
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           This file is in the  public domain because it was solely created by  NASA. NASA copyright policy states that "NASA material is not protected by copyright unless noted". (See  Template:PD-USGov,  NASA copyright policy page or  JPL Image Use Policy.) | 
           
            
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        Imagen tomada de  en.wikipedia.org/wiki/Image:Einstein_gyro_gravity_probe_b.jpg
        
        
        
       File usage
       
        The following pages on Schools Wikipedia link to this image (list may be incomplete):
        
        
       
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