@sundogplanets My daughter and I built a Hadley telescope this past winter. We set it up in the backyard to test the initial collimation and focus.

We pointed it at Jupiter, and could see a white orb, cool, but there were repeated artifacts across the view that we couldn’t get rid of — something reflecting oddly in the mirrors.

After much fussing, we both came to the same realization: They were the Galilean *moons*! Absolutely blew our minds that we could see them through our homemade scope.