Skynet:

Just as the sun sets or rises, one can often see the shadow of the Earth rise or set in the opposite direction. The effect lasts only a couple of minutes. In this photo, taken at about 35,000 feet over the Turks & Caicos, the sun is rising to the right, and the shadow is setting to the left. The sharp purple shadow of the curve of the Earth lasted only a minute or so. This is the only "terminator" you will see.