My nephew was visiting. He's an exceptionally bright kid, probably on the spectrum, but highly verbal and outgoing. It's just that he sees everything and lacks a filter. So when we took him to visit a young friend who had build a model of the solar system, I had to warn my nephew not to point out any errors. There were bound to be errors, of course, because no matter how carefully you measure, you can't build a whole solar system out of styrofoam and fishing line. Our young friend had certainly tried his best. This was no mere coat hanger science project. It filled a large room, and in addition to the styrofoam and fishing line, there was a projector that created a horizontal screen of light that showed more stars. Maybe it was a whole galaxy, not just a solar system. There were a lot of things, whatever it was. My nephew was trying to tell me that the projection looked different from above than from below, so I lay down and looked up, and asked him to put a finger throug...