So if you take a cross section of a wing and sometimes you can see this. You have a pocket of air that the moving wing is passing through. And the air wants to stay as one parcel, so it travels faster on top than bottom. So fast moving air has lower pressure. Neil deGrasse Tyson: I don't know if we're going to be listening to this and who's going to be watching it? But you can take a ribbon. It doesn't matter what paper you do use, but I'll get a nice long skinny strip from that. There it goes. Now I'm going to blow across it. Here I go. All right.