title: How does the geospatial $nearSphere operator interact with LineString and Polygon
body: <p>According to the documentation, a <a href="http://docs.mongodb.org/manual/core/2dsphere/" rel="nofollow">2dSphere geospatial index</a> can also be used for complex GeoJSON shapes like LineString's and Polygon's which consist of multiple nodes.</p>
  
  <p>When you search a field filled with such complex shapes with <a href="http://docs.mongodb.org/manual/reference/operator/nearSphere/" rel="nofollow">$nearSphere</a> for proximity to another GeoJSON object (which can potentially also be a complex shape), how will the distance of these shapes be calculated?</p>
  
  <p>Will it compare the closest nodes of the shapes? The most distant nodes? Some average of the nodes? The closest point on any of the edges of the shape?</p>