why do the poles experience about six months day and six months night?
The Poles experience about six months of day and six months of night because of the tilt of the Earth on its axis. Because of this tilt, each Pole is tilted towards and away from the Sun for about six months each.
When the North Pole is tilted towards the Sun, it experiences continuous daylight for six months. It is night for the same time period at the South Pole. These conditions are reversed when the South Pole is tilted towards the Sun.