Christianity & Astronomy Before the Telescope
Christianity is often cited as the reason behind a 1,500 year gap in astronomical knowledge. But others claim that the Church supported astronomy.
As usual, the truth is somewhat more complicated.
A Brief History of Astronomy Before the Telescope
My first real video is up on my YouTube channel.
Astronomy Before the Telescope
In an effort to reach a wider audience, I have decided to start a podcast as a YouTube channel.
To begin, I’ll be converting many of my classes that I’ve created for the SCA into videos. But this channel will also allow me to create content that doesn’t fit into the normal ~50 minute class block at SCA events.
I have a lot planned for this and it will probably be distracting from progress on the Almagest for awhile.
But, for now, here’s a brief intro to the channel.
Almagest Book XI: Calculating Planetary Longitude
With both the planetary mean motion tables, and the tables of anomaly, we’re now ready to calculate planetary longitude.
As with before, Ptolemy explains how this is to be done, but doesn’t provide an example. As such, I’ll follow along with example $14$ from Toomer (in Appendix A). Continue reading “Almagest Book XI: Calculating Planetary Longitude”
Almagest Book XI: Planetary Tables of Anomaly
Chapter $11$ of this book is simply the Planetary Equation Tables. I have transcribed them and make them available as a Google Sheet. Continue reading “Almagest Book XI: Planetary Tables of Anomaly”
Almagest Book XI: Constructing the Tables of Anomaly
In the last chapter, Ptolemy walked us through a light proof on how to find the apparent position of a planet. But, immediately in this chapter, Ptolemy tells us that going through that process every time is troublesome:
[A]lthough that method is the only one which provides a fully accurate solution to the problem, it is too cumbersome to be convenient for [astronomical] investigations.
What is Ptolemy’s solution?
As you probably expect, it’s to make tables that allow us to calculate quickly:
We have constructed, for each of the five planets, a table which is easy to use as we could devise, while at the same time being very close to full accuracy.
In this chapter, we’ll follow along as Ptolemy explains how they are laid out.
However, Ptolemy’s description is not well explained, so I will interweave this with a more comprehensive explanation based on Neugebauer’s History of Ancient Mathematical Astronomy. Continue reading “Almagest Book XI: Constructing the Tables of Anomaly”
Almagest Book XI: Finding the True Position
Our next goal will be to determine how,
given the arcs of the periodic [motions] on the eccentre which produces the uniform motion [i.e., the equant] and on the epicycle, one can readily obtain the apparent positions of the planets.
Continue reading “Almagest Book XI: Finding the True Position”
Almagest Book XI: Saturn’s Epoch Position
Our next step is to determine the epoch position for Saturn. Continue reading “Almagest Book XI: Saturn’s Epoch Position”
Almagest Book XI: Saturn’s Periodic Motion
Ptolemy now walks us through his supposed method for determining the periodic motions of Saturn. I say “supposed” because, again, Ptolemy’s final result doesn’t quite match what he tells us here. But we’ll follow along anyway.
As usual, he begins with an observation from the Babylonian astronomers: Continue reading “Almagest Book XI: Saturn’s Periodic Motion”