One of the most obvious measurements that can be made of a star is its luminosity, or brightness. Hipparchus set up a system over two thousand years ago. We use this system of stellar magnitudes still today. It is a ranking system, where a lower number means a brighter star. Hipparchus was not very quantitative in his system so Norman Pogson established a mathematical definition of magnitude in 1856. You will find that star charts often have the magnitudes of stars printed on them. How faint of a star could you see with your unaided eye? It depends on where you live. Southeast Michigan is a terrible place to try to do astronomy. Just look at this map! Is there anywhere in the world that is better? But all of this so far is about apparent magnitude as opposed to absolute magnitude. Absolute magnitude is different in that it eliminates the effects of a star’s distance from Earth. In this table, you can see a pattern in how the apparent magnitude is different from the absolute magnitude. Which brings us to the concept of the Distance Modulus, an excellent way to determine a star’s distance.