The polar explorers of lore speak of a phenomenon they called a 'mirage' where the sun would appear in the sky at locations that they could not explain. Oft times, this so-called 'mirage' would look very red and 'brazen' in color. What makes this most curious is the fact that these explorers were extremely adept at telling their location from the layout of the stars and the position of the sun. The further these explorers would proceed north, the more erratic their passage north would become, until finally they would be forced to turn backwards until they regained their bearings. This confusion can be easily explained by the unexpected curvature of the earth they encountered as they approached nearer the opening into the inside of the earth. The phenomenon they titled a 'mirage' was actually the sighting of the inner sun rising over the horizon of the inner earth opening.
Begin watching the video at 3 min. 20 sec. to hear a description of how Chinese scientists experienced the same phenomenon during their expedition north to find a land where the sun does not shine.