What’s the difference between an astrolabe and an equatorium?
This is a question I’ve been asked several times, and it’s a reasonable one given that this blog is called “Astrolabes and Stuff”, yet I’ve mainly been posting about equatoria. So I’m going to answer it in this post. First, it’s important to stress the one thing astrolabes and equatoria have in common. They are both tools, calculating devices. As such, they simplify (and approximate) tasks that could have been done by geometrical calculation – but the astrolabe and equator