Why the Midnight Sun and Polar Night Occur
The principle behind the midnight sun and polar night, when the sun never sets or never rises at high latitudes.
It's due to axial tilt
Earth's rotation axis is tilted about 23.4° relative to its orbital plane. Because of this, high-latitude regions have the sun above the horizon all day, or below the horizon all day, depending on the season.
Midnight sun and polar night
- Midnight sun: at high latitudes in summer the sun never drops below the horizon, so it stays bright even at night.
- Polar night: in winter the opposite happens — the sun never rises above the horizon, so it stays dark even during the day.
Where you can see it
It occurs within the Arctic Circle (latitude 66.5° or higher) and the Antarctic Circle. Northern Norway, Iceland, and Finland are famous for the midnight sun.
When there is no sunrise or sunset on a given date, this calculator indicates a midnight sun or polar night. Check it yourself in the summer- and winter-solstice tables of a high-latitude city.