You sneak into the beautiful observatory and see a colossal astrolabe that fills the entire room, precisely positioning the nearby solar system objects in exquisite detail. It moves silently, tiny gears spinning at great speeds in order to move the giant ones slowly, but oh so precisely. But, hm, maybe not entirely accurately. You notice that... yes... without a doubt... the moon is a tiny bit off in this model. Just a small hair, but enough for your eye to notice. You feel a need to fix it.