Is this a giant hole in space?  I show a picture similar to this as I ask this question to students and audiences that I host in my planetarium.  Most people answer that it is a black hole, or dark matter, or dark energy, or something strange like that.  But the amazing thing is that it is actually a thick cloud of dust that is opaque, letting no visible light from the distant stars pass through. The funny thing is that the cloud is transparent in infrared light, but in the visible spectrum it highlights something interesting about the universe:...