Where does the midnight sun come from?

The polar regions are known for the polar night, an almost unbroken winter night. In summer, on the other hand, the days grow longer and longer. The phenomenon is the same at the North Pole (boreal) and the South Pole (austral). It is called the polar day, or the midnight sun.

In the Northern Hemisphere, the days quickly grow longer from the spring equinox (around March 20) and reach their longest at the summer solstice, on June 21. At that point, regions above the Arctic Circle experience an unbroken day during which the sun shines for 24 hours. The sun sinks toward the horizon in the evening but does not set: after midnight, it slowly climbs back into the sky for a second day without night. This is called the midnight sun. Areas just below the Arctic Circle get a white night (as opposed to a dark night), meaning the sun does set, but only for a few hours, before rising again very early. During this very short night, the sun, although set, does not dip far enough below the horizon for the night to become completely dark. The pale glow is bright enough to read a book without artificial light. The higher the latitude, the longer this summer day lasts: at the pole, it is light for 6 months, then dark for 6 months in winter.

Under cloudy or overcast skies, all you will see is a pale, diffuse, half-twilight glow, but when the sky is clear, the northern atmosphere produces an astonishing light. While the daytime looks much like it does at our latitudes, the light of the evening and of the white night can resemble the light seen during an eclipse, with the sun low on the horizon. It is a kind of sunset that never sets. The explanation lies in the tilt of the Earth’s axis relative to the sun. This axis shifts with the seasons: in summer, the sun lights the Northern Hemisphere more, shining constantly at the pole. In the Southern Hemisphere, where the seasons are reversed, it is completely dark during that time.

White nights can be seen from Iceland and northern Scotland to Scandinavia, the Baltic Sea and Russia (Saint Petersburg). To enjoy the midnight sun, though, you need to reach at least the Arctic Circle. In Europe, it crosses the north of Iceland and Scandinavia (North Cape), then northern Russia (Murmansk): up there, you can truly admire the midnight sun shining 24 hours straight…

Source: National Geographic, Kieran Mulvaney, article published May 25, 2023