Mark Sizer: You are exactly right: The sunspot count is based on the ones we can see. Until the space age that was all scientists had, and for consistency the count is still maintained in that manner. However, there are in-space solar telescopes now that look at the entire solar globe, so that scientists will know what’s happened on the far side.

While that exists at any given moment, it’s not really a “thing”, is it? The sun rotates and we revolve so the Earth-facing hemisphere is a different part of the sun from time-to-time, right?

Oh, great. It’s even worse “Because solar rotation is variable with latitude, depth and time, any such system is necessarily arbitrary”. I forgot that the surface of the sun also isn’t a “thing”. I do find it interesting that the sun’s (arbitrary) rotation period and the moon’s revolution period are about the same.

Basically, these are the ones we count because they’re the ones we can see. Isn’t there something looking at the other side, these days?