Very cool every time I see one.
Yes, telescope guy, it was in the early 70s. I subscribed since early ‘71 but my brother had a mix of earlier issues laying around.
Originally done with film it’s a difficult exposure(s). Bumping the camera, accidental overexposure, could easily ruin one year of images.
A company called Solarscan uses a pinhole camera in an aluminum can body to hold a single positive exposure print. In other words the sun trails appear black on the paper, and a scanner can flip the image. Costs less than $25, from England. I have a 3 month scan that turned out so-so.