28 May 2015

What did R' Zacuto Change about the Astrolabe?

I haven't gotten to the library yet. Meanwhile, I can't figure this out.
Everyone knows he did something brilliant to the astrolabe but if you look it up online every website says it was something else.
He was the first to make an iron astrolabe. No, he was the first to make a copper astrolabe. No, he was the first to make a mariner's astrolabe. No, he was the first to make a spherical astrolabe.
Astrolabes are beautiful things and I would love to be able to walk into class with one and say, “This is a Zacuto astrolabe, and here is how you use it.” But what was it?

Taking the average, it appears that he was the first to make the mariner's astrolabe out of metal instead of wood, thus preventing it from warping.
I hope to post some final answer to the question, as well as a useful application of the mariner's astrolabe for the use of high school students. Check back.


  1. Just sharing rumors, but... I was under the impression he made the first metal (copper) astrolabe, but his real innovation was pairing it with astronomical tables and maritime charts. Combined, one could get results regardless of where one was on the globe that were precise enough to make the Age of Discovery possible.

  2. Also puzzled as to how the rumor that Zacuto "invented the first metal astrolabe" got started. Metal (non-wood) astrolabes had been around LONG before Zacuto. (Images of early non-wood astrolabes are available online)