This post a collection of my class materials which will be posted below the fold. In general, this is a Powerpoint presentation and the script I follow is included in the file. Continue reading “Class Materials”
Data: Stellar Quadrant Observations – 5/27/2022
The weather this year has been frustrating. Winter held on far longer than normal. While temperatures weren’t freezing in March and April, they stubbornly refused to get into a temperature range that would allow me to open the windows. Then, after a few nice days, it immediately jumped into the early summer. Needless to say, such turbulent weather is not good for observing and I’ve only been out twice this year1
However, temperatures have cooled back off and, should a clear night occur, it would be a quite pleasant night to observe. This past Friday, despite solid cloud cover all day, the weather reports said it should clear by around $8$pm, so I headed out to Danville with the quadrant to do some observing. Although there was some high humidity, an adjustment in how I select what objects to observe made this likely one of the most productive observing sessions I’ve yet had. Continue reading “Data: Stellar Quadrant Observations – 5/27/2022”
Queen’s Prize 2022 – The Astronomical Epoch for Solar and (First) Lunar Models
Thanks to Corona, it’s been quite awhile since we’ve really had an Arts & Sciences competition here in Calontir. While we had a virtual Kingdom A&S in $2020$ the last one we had in person was Queen’s Prize in $2019$.
However, this past weekend we finally had another in person Queen’s Prize and I entered my latest paper revising Ptolemy’s models for use in the present day. My previous entry attempted to update the solar model but contained critical errors2. This was revealed when I started attempting to update the lunar model. Realizing that it was predicting solar positions that would have made the eclipses necessary to calibrate the lunar model impossible, I revisited the solar model and made the necessary corrections.
That, plus the first lunar model were included in this year’s entry which was rewritten using LaTeX for a smoother editing and reading experience as Google’s equation editor was rather poor. The paper ended up being $62$ pages (although roughly $45\%$ of that was front material and appendices) which was a lot to expect anyone to read. As such, I also created a TL;DR version for passerbys.
Continue reading “Queen’s Prize 2022 – The Astronomical Epoch for Solar and (First) Lunar Models”
Spinoff Project Ideas
Frequently, when working on my astronomical research, I come up with interesting ideas for projects that I would love to tackle, but simply don’t have the time or may not have particular skillset to dive into. This post is intended to be a list of those ideas. Continue reading “Spinoff Project Ideas”
Almagest Book VII: On Precession
At the beginning of the last chapter, Ptolemy noted that the celestial sphere appears to have a rearward motion of its own known as precession of the equinoxes. This motion means that the position of the sun in the zodiacal signs slowly increase in advance as time passes. In particular, the sun was at the beginning of Aries in Ptolemy’s time, but since then has advanced such that today it lies near the beginning of Pisces.
We can see this mainly from the fact that the same stars do not maintain the same distance with respect to the solstical and equinocital points in our times as they had in former times: rather, the distance [of a given star] towards the rear with respect to [one of] the same points is found to be greater in proportion as time [of observation] is later.
Almagest Book VII: Ptolemy’s Star Alignments
Having laid out Hipparchus’ alignment, Ptolemy offers several of his own
in order to provide those who come after us with a means of comparison.
Continue reading “Almagest Book VII: Ptolemy’s Star Alignments”
Almagest Book VII: Hipparchus’ Star Alignments
Ptolemy lays out the arrangements described by Hipparchus by going through stars in various constellations:
Stars in Cancer. [Hipparchus] records that the star in the southern claw of Cancer [α Cnc], the bright star which is in advance of the latter and of the head of Hydra [β Cnc], and the bright star in Procyon [α CMi] lie almost on a straight line. For the one in the middle lies $1 \frac{1}{2}$ digits to the north and east of the straight line joining the two end ones, and the distances [from it to each of them] are equal.
First, we should discuss the identification of the stars. The designations of the stars in the brackets are the modern Bayer designations first created in $1603$. For Ptolemy’s part, he described the positions of the stars based on how they should appear in the representation of the constellation. For example, we see him here describing α Cnc as the “southern claw of Cancer”. However, because the depiction of the figures in constellations is somewhat subjective, this leads to some ambiguity in which stars are which, making assessing the validity of Ptolemy’s statements somewhat difficult. Continue reading “Almagest Book VII: Hipparchus’ Star Alignments”
Almagest Book VII: On the Relative Positions of the Stars
Now, to deal with the next part of the theory, we shall begin discussing the stars, and first, in accordance with the logical order, the so-called fixed stars.
To introduce the next book of the Almagest, Ptolemy informs the reader that we will be taking some time to understand the fixed stars. There are two important things to note about this sentence. The first is that Ptolemy is taking extra care to make sure the reader knows we are discussing the fixed stars. This is because the Greek concept of “stars” could include the planets. Continue reading “Almagest Book VII: On the Relative Positions of the Stars”
Almagest Book VI: Determining the Inclinations
And here we are. Final chapter of Book VI. Here, we’ll finish out Ptolemy’s discussion of the inclinations of eclipses. In the previous post, we discussed a few things we’ll need to determine that3, but we really haven’t discussed is what the “inclination” means. So I’ll begin by doing that as Ptolemy doesn’t really do a clear job of doing so. Continue reading “Almagest Book VI: Determining the Inclinations”
Data: Stellar Quadrant Observations – 5/7/2022
While last night wasn’t a particularly good night for observing, with high humidity and a nearly first quarter moon, but as my girlfriend is in town and has wanted to try observing with me, we headed out to Broemmelsiek park last night and did a bit of observing. Continue reading “Data: Stellar Quadrant Observations – 5/7/2022”