What causes Alaska to have 6 months of day and 6 months of night?

Answer 1

No location, even in northernmost Alaska, has 6 months of day or night.

Only the North Pole or the South Pole will have 6 continuous months of daylight and 6 continuous months of night, because they are alternately tipped toward or away from the Sun. Only one half of a planet (sphere) can be illuminated at any one time. A pole, the end of a planetary axis, is either tilted toward the sun, and stays in the Sun as the Earth spins, or tilted away from the Sun, and cannot move into daylight.

Areas within the Arctic Circle or Antarctic Circle (a latitude of 66.6 degrees or more) will experience one or more days of 24 hours of sunlight, and conversely one or more days of 24 hours without sunlight. The closer one gets to a pole, the longer or shorter this period of continual day or night, which is popularly described as the "midnight sun" and the "polar night." The effect of twilight reduces the actual periods of nighttime darkness, but the Sun will also never rise very high in the sky even in summer.

Locations that experience the phenomenon are northern parts of Alaska (US), Canada, Greenland (Denmark), Iceland, Finland, Norway, Sweden, and Russia. In Svalbard, Norway, the sun does not set in summer, but circles the horizon from April 19 to August 23. Large uninhabited areas of Antarctica also experience extended days and nights, but only near the South Pole are they about 6 months long.