Some stars shine brighter than others

I found this on the wall of one of the labs today. What an excellent idea! It shows that some stars are actually closer than others. In truth, some stars really do shine brighter than others but a bright star that is a long way off might look dimmer than a star that was not so bright but was closer. This is what they call "apparent magnitude". A fair test would be to line up all the stars at the same distance. Then you'd know which was brightest. They call that "absolute magnitude". The distance chosen is 10 parsecs away and since we can't actually do it, absolute magnitude is calculated.