Constellations are patterns of stars that (due to the Earth's rotation) appear to move across the sky together. But are the stars in a constellation physically related in some way? In particular, can you tell, simply by looking at them, if they are at similar distances from the Earth? (If in doubt, look up in Wikipedia the distances in light years of the three stars in Orion's Belt, Alnilam, Alnitak and Mintaka .)