In order to explain day and night, time zones, and the seasons, some flat Earth conjecturists propose that the Sun does not emit light in all directions, but acts more like a spotlight, only illuminating part of the flat Earth at a time.claimed by http://www.theflatearthsociety.org/forum/index.php?topic=58309.0#.VuJqbULlyPZ This conjecture is not consistent with observation: At sunrise and sunset, a spotlight Sun would be up in the sky at least a little bit, rather than at the horizon where it is always actually observed. A spotlight Sun would also appear at different angles in the sky with respect to a flat ground than it does with respect to a curved ground. Assuming light travels in straight lines, actual measurements of the Sun's angle in the sky from locations very distant from each other are only consistent with a geometry where the Sun is very far away and is being seen from the daylight half of a spherical Earth. These two phenomena are related: A low-altitude spotlight Sun would spend most of the day near the horizon for most locations on Earth, which is not observed, but rise and set fairly close to the horizon. A high-altitude Sun would spend more of the day away from the horizon, but rise and set fairly far from the horizon, which is also not observed.
