> but had no idea that MST/solar is 17 minutes off - that's a lot!

[This Wikipedia article](https://en.wikipedia.org/wiki/Solar_time#Mean_solar_time) has what I think is a good intuition here:

> Long or short days occur in succession, so the difference builds up until mean time is ahead of apparent time by about 14 minutes near February 6, and behind apparent time by about 16 minutes near November 3.

With the really nitty gritty being here: https://en.wikipedia.org/wiki/Equation_of_time#Concept

> Of course there's also the difference between this and proper clock time (depending on where in your timezone you're located), and the clock shows clock time.

"Standard time", yes, will be different yet. I didn't comment on that b/c the whole article is, of course, building a clock that unmoors us from cultural conventions, and I think Standard Time falls very squarely in the "cultural convention" bucket. So it's more of a solar clock in that sense.