The Arctic Circle is the imaginary line at 66 degrees 33 minutes north. It marks the lowest latitude at which the sun remains above the horizon for 24 hours in the summer and below it in the winter. The Arctic Circle is home to the largest number of people in the world.
Nocturnal
Nothing is darker than midnight, and this phenomenon is not limited to the middle of the year. Midnight sun is also possible at the poles. In general, the number of days of the year when midnight sun is possible increases the closer you are to one of the poles. The midnight sun can be seen up to 90 km beyond the polar circles, though the exact latitudes vary slightly year-to-year due to differences in topography.
In the northern hemisphere, the summer solstice is around 21 June, while the winter solstice is around 21 December. This phenomenon is most common in areas where the polar circles cross, like Iceland. The southern hemisphere, on the other hand, does not experience this phenomenon. The countries that experience midnight sun include Iceland, Canada, Finland, Norway, and Russia. It is also possible to experience the phenomenon in Alaska, which is home to the city of Murmansk.
Disc-shaped
The novel Nothing is Darker than Midnight and It lasts one minute tells the story of the midnight sun. The term midnight sun can apply to many regions around the world, including the Arctic Circle and Antarctica. It is also used to describe the time of day when the sun sets. At certain latitudes, however, the period of daylight is more than six months long. The northernmost regions of the United Kingdom experience twilight throughout the night, especially around the summer solstice.
Observed in other latitudes
Latitude is a measurement of location relative to the Equator. There are two types of latitudes: geocentric latitude and astronomical latitude. Both are given in degrees north of south of the equator. The geocentric latitude is the more precise of the two types and is the one most commonly used.