Now it’s time to determine the small angles that get applied as corrections. As with before, we’ll start with the first opposition, again using the same diagram. Continue reading “Almagest Book X: Second Iteration Correction for Equant – First Opposition”
Almagest Book X: Second Iteration for Mars – Part 2
Continuing on with our second iteration in which we calculate the revised line of apsides and eccentricity of Mars’ model.
As with before, I’m doing my calculations in a Google Sheet to make it easier to correct should I make an error. This also means that the Sheet will be keeping much higher precision to prevent rounding errors. However, as I’m only showing rounded values, things may look a bit off. So if something seems funny, I encourage checking out the aforementioned Sheet. Continue reading “Almagest Book X: Second Iteration for Mars – Part 2”
Almagest Book X: Second Iteration for Mars – Part 1
Chapter $7$ of Book X has been a lengthy one. We already have six posts behind us and we’re really just getting started because now we have to repeat all of those posts again, iterating through to better approximate an angle we didn’t know at the outset.
To do a quick review, in the first post in this chapter, we needed $\angle ZNH$, the apparent change along the equant circle from the point of view of the observer in the diagram below.
However, what we had was $\angle LNG$ which was the apparent change along the ecliptic from the point of view of the observer.
As you can tell, they’re close, but not quite the same. However, we could get to what we needed from what we had by subtracting $\angle LNT$ and $\angle YNM$.
We found both of these angles to be $0;33º$ in this post and $0;50º$ in this post, respectively.
Unfortunately, both of those values were calculated starting from an incorrect value for $\angle ZNH$. But, the good news is that applying them anyway will (Ptolemy hopes) still get us closer to the correct value! And then we’ll be able to iterate through again to reduce the discrepancy even further.
So let’s get started. Continue reading “Almagest Book X: Second Iteration for Mars – Part 1”
Pseudo-Ptolemy’s Treatise on the 9 Types of Comets
Starting around the 13th century, various astronomical texts began making their way into Christian Europe. These texts were largely translated from Arabic.
Among them, was a text that was originally attributed to Ptolemy which discussed the character and astrological implications of comets. Scholars have since concluded that this text is not by Ptolemy, but it was still widely distributed.
This text is one of many that is under investigation for the Ptolemaeus Arabus et Latinus project. There they provide a scan of a manuscript in the collection of the British Library (Sloane 2030) as well as a transcription of the text.
However, there was no translation. As such, I have attempted my own which is placed below the fold.
Continue reading “Pseudo-Ptolemy’s Treatise on the 9 Types of Comets”Class Schedule for Pennsic 2024
Pennsic is only a few short weeks away and as usual, I’m teaching a whole host of astronomy classes.
This will include my previous classes but will also be introducing a new class on comets in the SCA period.
Full schedule beneath the fold.
Continue reading “Class Schedule for Pennsic 2024”Posting Will be Slow
Work on the Almagest is going to be slow for me for the next several months. The particular portion that follows the last post is especially challenging because Ptolemy repeats the long procedure he just went through over the course of the last five posts, in an iterative manner. However, he doesn’t show any of the work – just the final results. Thus, it’s going to take me a long while to get through all of that to post about in the first place.
But on top of that, I’m the event steward for two events in my barony in the next year as well as helping with others. Thus, a lot of my free time has been devoted to those.
Hopefully, I’ll find some time here and there to work on this project, but it will certainly be slow.
Almagest Book X: Correction for Equant – Third Opposition
In the previous two posts, we’ve been looking at how the apparent position of the center of a superior planet’s epicycle shifts position along the various circles. Specifically, we’ve been looking at how the angle between oppositions differs between the eccentre of mean distance and the equant circle.
In this post, we’ll do the same for the third opposition Ptolemy gave us. Unsurprisingly, the process will be largely the same as in the past two posts. Continue reading “Almagest Book X: Correction for Equant – Third Opposition”
The Almagest Manuscripts – State Library of Victoria: RARESF 091 P95A
I have finished adding another Almagest manuscript to the collection in the Google Sheet. This time, it’s the RARESF 091 P95A manuscript1 at the State of Victoria Library in Australia and it has some interesting features. Continue reading “The Almagest Manuscripts – State Library of Victoria: RARESF 091 P95A”
Almagest Book X: Correction for Equant – Second Opposition
Having determined a correction for the equant for the first opposition, we’ll now repeat the procedure for the second. The diagram to do so is identical to the previous one, but is flipped over the line of apsides. Continue reading “Almagest Book X: Correction for Equant – Second Opposition”
Data: April 8, 2024 Total Solar Eclipse
This past Monday, I spent the day in Mountain View, AR with one of the members of my Barony and their family to catch the eclipse. Continue reading “Data: April 8, 2024 Total Solar Eclipse”