I donβt know if I would say theyβve βleft the planetβ in low earth orbit. They went to space, but theyβre still very much gravitationally bound to earth. If their orbital velocity were to suddenly become zero, they would fall to earth very quickly. The people who went to the moon left the planet.
But to answer your question, the fact that we harnessed electricity to create a communications network that can instantly communicate from anywhere on earth to anywhere else nearly instantly, still amazes me.