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Diffraction Spikes
@diffractionspikes.bsky.social

Want to relate a fun story of students going above and beyond that relates to one of my favorite things to spend time on -- PSU astronomy history. First off, in many pictures of Old Main, the armillary sphere that was the class gift of 1966 is featured.

Diffraction Spikes
@diffractionspikes.bsky.social

Years ago, one of my (now retired) colleagues posed the question, "What's wrong with this armillary sphere?". It took me a while to notice the error, but the one he and I talked about way back when was that the constellations of the Zodiac are shown on the equator, not the Ecliptic.

Diffraction Spikes
@diffractionspikes.bsky.social

So I like to pose this as a challenge question in classes where I teach about the Ecliptic. I show them a picture, tell them they walk by this landmark every day, and then I tell them if they can spot an error on it, they get extra credit.

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Diffraction Spikes
@diffractionspikes.bsky.social

Well, I posed this question to my class of first year undergrads this spring semester, and two of them came back having found a second error! They pointed out that the constellations of the Zodiac are not aligned with the proper dates (e.g., this shows Pisces on the winter Solstice).

Diffraction Spikes
@diffractionspikes.bsky.social

So my conclusion is, one, it is always a treat to get to work with students who like to geek out over the same things I do, and two, sorry class of 1966, but you got sold a pretty badly designed armillary sphere that gets its astronomy all wrong.