Having completed the preliminary models for the inferior planets, Mercury and Venus, Ptolemy now turns his attention towards the superior ones: Mars, Jupiter, and Saturn. Continue reading “Almagest Book X: Preliminary Comments Regarding the Models for Superior Planets”
Almagest Book IX: On the Order of the Spheres
Having laid out “the sum total of the chief topics one may mention as having to do with the fixed stars, in so far as the phenomena [observed] up to now provide the means of progress in our understanding” Ptolemy now moves on to “the treatment of the five planets” each one getting a book to itself.
But before diving in, Ptolemy first proposes that we “avoid repetition” by “explain[ing] the theory of the [planets] by means of an exposition common [to all five], treating each of the methods [for all planets] together.”
Beginning this discussion, Ptolemy introduces us to the order of the spheres for these planets, the sun, and moon. Continue reading “Almagest Book IX: On the Order of the Spheres”
Data: Stellar Quadrant Observations – 12/21/2020 (Great Conjunction)
Last night was the much hyped Great Conjunction of Jupiter and Saturn. I was asked if this had any meaning for my project. It really doesn’t have any special astronomical meaning, but it was fun to look at through a telescope. However, I decided that this would be an interesting stress test for the quadrant. After all, Jupiter and Saturn were only $6$ minutes of arc apart. This is a single division on the quadrant’s scale. So could I actually tell them apart? Continue reading “Data: Stellar Quadrant Observations – 12/21/2020 (Great Conjunction)”