The Dark Side

When I was still in elementary someone told me that during an airplane flight he saw a part of the earth where day and night were both visible. I didn't have the chance to validate this until I got work that required me to board long-haul destinations like LA. On my return flight to Manila, I tried to stay awake the whole time waiting to see this natural wonder. I got impatient so I asked the lady seated beside me if it was true... and, well... hehehe I wasted my neurons.