ith experience, you should be able to visually estimate magnitude differences as small as 0.1. When you're confident you can do this, consider
Build A Parallax-measuring Tool
Hold up a finger and look at it with just one eye, then switch to just the other and you'll see your finger appear to ‘jump’ from side to side. The further away the finger, the smaller the jump. This apparent shift of a nearby object against a distan
