title: Attaching child nodes/objects to an Object3D in three.js
body: <p>I'm loading an .obj file into a Object3D object.  That's working well and I can see it on the screen.  However, I would like to create the impression of spinning sprites (fireflies, lightning globes, that sort of thing) at certain points above the object.</p>
  
  <p>I've been looking over the three.js documentation on sprites and other things, and am very impressed with the capabilities.  But I need a little help on how to create a standalone sprite 'globe' as it were, with sprites flying about in their own local coordinate system, then moving that standalone 'globe' to a point above the obj file.  Could someone help me get started with this?  (I guess it comes down to, how do you position one object relative to another in threejs?)</p>