The places on Earth where the sun never sets experience continuous daylight, known as the Midnight Sun or Polar Day. This phenomenon occurs during the summer months in the polar regions, where the sun remains visible above the horizon for 24 hours a day. This effect creates a world of perpetual daylight that lasts for days or even months.
The Science of Polar Day
The occurrence of continuous daylight is a direct consequence of the Earth’s approximately 23.5-degree axial tilt relative to its orbit around the sun. This tilt causes one pole to be constantly angled toward the sun during its summer season, preventing the sun from dipping below the horizon as the Earth rotates. This results in the sun circling the sky without setting.
The boundary for this phenomenon is defined by the Arctic Circle (66°34′ N) and the Antarctic Circle (66°34′ S). Locations poleward of these lines experience at least one 24-hour period of continuous daylight around the summer solstice. Due to atmospheric refraction, the Midnight Sun can be observed at latitudes slightly closer to the equator than the theoretical circle, meaning the sun can appear above the horizon even when it is geometrically below it.
Geography of Continuous Daylight
The vast majority of human settlements that experience the Polar Day are found in the Arctic, as the Antarctic Circle mainly encompasses the uninhabited continent of Antarctica, save for a few research stations. Countries and territories crossed by the Arctic Circle include a collection of North American and Eurasian nations.
European Locations
Norway is famously known as the “Land of the Midnight Sun,” with regions like North Cape and the city of Tromsø experiencing continuous daylight for weeks. The Norwegian archipelago of Svalbard, one of the northernmost inhabited regions, has continuous daylight from approximately April 19 to August 23. Neighboring countries Sweden and Finland also feature large areas within the Arctic Circle. Murmansk, Russia, stands as the largest city north of the Arctic Circle, enjoying about two months of Midnight Sun.
North American Locations
North America’s locations include parts of the United States, Canada, and Greenland. In Alaska, the city of Utqiagvik, formerly known as Barrow, is one of the most accessible places to observe the phenomenon, as it is situated far north of the Arctic Circle. Canada’s Yukon and Northwest Territories also have communities that experience the continuous daylight. While most of Iceland lies just south of the Arctic Circle, the small island of Grímsey straddles the line and experiences the Midnight Sun.
Duration and Seasonal Variation
The length of the continuous daylight period varies significantly based on a location’s exact latitude. On the Arctic and Antarctic Circles themselves, the sun remains above the horizon for only a single 24-hour period, which occurs on the summer solstice around June 21 in the north. As one travels further poleward from the Circle, the duration of the Polar Day rapidly increases.
In the northernmost part of Finland, the sun stays above the horizon for 72 consecutive days during the summer. The most extreme duration is found at the geographic North and South Poles, where the sun is continuously visible for nearly six months, rising and setting only once per year around the equinoxes. The Northern Hemisphere’s Polar Day occurs between late March and late September, peaking around the June solstice. Conversely, this period of constant daylight is balanced by the Polar Night during the winter, when the sun remains below the horizon for 24 hours or more.