The method is similar to that used by surveyors. We have a very skinny triangle on the sky. Determining Distances Parallax is measured in arcseconds. As stars get further away, their parallax becomes smaller. Importance of Parallax Distances Parallax is the key to knowing distances in the universe.
Nearby stars are the stepping stones to measuring the distances to everything else in the universe.
If all stars were at the same distance, it would be easy to compare their properties. Use the inverse square law to find what it's brightness would be at a standard distance. Absolute Magnitude Astronomers adopt 10 pc as the standard distance. It is 10 times the standard distance. Thus, it would be 100 times brighter to us at the standard distance.