{"id":5357,"date":"2026-07-04T09:38:53","date_gmt":"2026-07-04T14:38:53","guid":{"rendered":"https:\/\/jonvoisey.net\/blog\/?p=5357"},"modified":"2026-07-04T09:38:53","modified_gmt":"2026-07-04T14:38:53","slug":"understanding-ptolemys-almagest-book-vi","status":"publish","type":"post","link":"https:\/\/jonvoisey.net\/blog\/2026\/07\/understanding-ptolemys-almagest-book-vi\/","title":{"rendered":"Understanding Ptolemy&#8217;s Almagest &#8211; Book VI"},"content":{"rendered":"<p><iframe loading=\"lazy\" title=\"YouTube video player\" src=\"https:\/\/www.youtube.com\/embed\/7o52fP5uV-U?si=W1jvg46vaGryzOCP\" width=\"560\" height=\"315\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p><!--more--><\/p>\n<p>Putting this video together was pretty challenging. The original script was 2 pages longer than the final version. This was mostly due to Chapter 6 in which we explore the possible eclipse intervals.<\/p>\n<p>While the concept in that chapter is pretty simple, Ptolemy&#8217;s execution is weird as he regularly flips back and forth between using the position of the moon about its inclined circle and the position of the sun about the ecliptic. I&#8217;ve yet to make complete sense of it, but it significantly muddies the water here. Originally, I went through each of the possible intervals he explores in some detail, but decided this was too much for what is meant to be a conceptual video. Thus, that chapter had to be completely rewritten.<\/p>\n<p>Chapter 4 was also a problem as it does a lot of the heavy lifting to set up Chapter 5 (exploring the eclipse windows) and I got lost in that foreshadowing instead of sufficiently explaining how Ptolemy approached finding the true syzygy from the mean.<\/p>\n<p>And speaking of syzygies, conjunction and opposition, I find that I have weird feelings about words sometimes. I have a positive association with the word &#8220;conjunction&#8221; and kinda dislike the word &#8220;opposition&#8221;. Thus, I had a\u00a0<em>large<\/em> number of instances in which I put &#8220;conjunction&#8221; into the script when I should have said &#8220;opposition&#8221;. This was, obviously, corrected, but that was a lot of re-recordings right there. And sometimes I just said syzygy even though specifying which type would have been entirely appropriate.<\/p>\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[24,83],"tags":[],"class_list":["post-5357","post","type-post","status-publish","format-standard","hentry","category-almagest","category-astronomy-before-the-telescope"],"acf":[],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p9ZpvC-1op","_links":{"self":[{"href":"https:\/\/jonvoisey.net\/blog\/wp-json\/wp\/v2\/posts\/5357","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/jonvoisey.net\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/jonvoisey.net\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/jonvoisey.net\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/jonvoisey.net\/blog\/wp-json\/wp\/v2\/comments?post=5357"}],"version-history":[{"count":1,"href":"https:\/\/jonvoisey.net\/blog\/wp-json\/wp\/v2\/posts\/5357\/revisions"}],"predecessor-version":[{"id":5358,"href":"https:\/\/jonvoisey.net\/blog\/wp-json\/wp\/v2\/posts\/5357\/revisions\/5358"}],"wp:attachment":[{"href":"https:\/\/jonvoisey.net\/blog\/wp-json\/wp\/v2\/media?parent=5357"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/jonvoisey.net\/blog\/wp-json\/wp\/v2\/categories?post=5357"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/jonvoisey.net\/blog\/wp-json\/wp\/v2\/tags?post=5357"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}