It's a Bluesky link but he use adult tags as de facto "spoiler" tags. The problem is that content is hidden if you're not logged into Bluesky. Here's a Bluesky mirror site to show the entire thread...
https://subium.com/profile/c0nc0rdance.bsky.social/post/3kpkcq2ecws22
A huge hint...
Show
latitude and longitude
just put the poles wherever it's convenient
idk, to me this is kinda semantics, whether or not we say a 2d surface in 3d space is 2d or 3d.
just assume "straight line" refers to a geodesic on the surface, then you can use whatever coordinates you want.