You can watch the sun setting from the bottom of a hill until it disappears from sight, climb in a car and drive to the top of the hill, and see the sun magically rising again while you drive, watch the sun setting again from the top, hop into a hot air balloon and see the sun rising again while you ascend, watch it set again while at a constant height, see a jet above you still in sunlight, so they have not seen the sun set yet, then later back down on the ground see the underside of clouds illuminated by the 3000 mile high sun that disappeared some time ago on a flat earth, yet its rays can still light up something above you. Wow, perspective is a strange beast! I guess something called curvature could explain this easily!