Question

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 .)

Answer 1

Purpose for the constellations is to help us to locate and identify the stars. On a really dark night, one can see thousands of stars. It is challenging to identify them. The constellations help by breaking up the sky into more manageable bits. They are used as mnemonics. Thus, the only relation between the stars of a constellation is that they form a particular structure, which we can relate to something, which is helpful in keeping their track. In fact, their distances from us can also differ by thousands of light years as in the case of stars from Orion's Belt.