I move around the world, starting from Sweden (where I live) going first to America, then continuing on to Australia, and then back to Sweden.
Explain the following:
The star constellations in the west horizon from Sweden will disappear below the horizon as I travel to America. And when I continue on to Australia, the constellations will appear just above the east horizon (from Australia). Perfectly reasonable on a round Earth. When I get back to Sweden, the star constellations will once again appear just above the west horizon, nothing has changed. If the Earth was flat, this would seem a bit strange.