How to use it
- Look at the blue line on the globe: the Arctic Circle.
- Type a place or press My location to see how far you are from it.
- Read the countries it crosses and the facts.
5 practical uses
- Plan a trip for the midnight sun or the northern lights.
- Check whether a town is north of the circle.
- Teach the polar day and the polar night.
- Find how far you are from the Arctic.
- See which countries the circle crosses.
The maths behind it
The circle is the parallel at φ = 90° − ε, where ε is the obliquity of the ecliptic, 23.4365° in 2026: at that latitude the sun's midday altitude at the winter solstice, 90° − φ − ε, is zero. Its length is 2πR sin ε = 15,995 km. The distance from a place to it along the meridian is R·|φ − (90° − ε)|.
What it is
The Arctic Circle is the parallel at about 66°34′N, 90° minus the Earth's tilt. On the June solstice the sun does not set anywhere north of it (the midnight sun), and on the December solstice it does not rise (the polar night). The farther north, the longer both last: at the circle itself one day each; at the North Pole six months each. Refraction and the sun's width in fact give the midnight sun a little south of the line too.
Where it runs
Through Norway, Sweden, Finland, Russia, the United States (Alaska), Canada, Greenland and, in the sea, Iceland's island of Grímsey. About four million people live north of it, most of them in Russia; Murmansk is the largest city, and Tromsø, Rovaniemi and Utqiaġvik are on the tourist maps for the midnight sun and the northern lights.
It moves
As the tilt decreases the circle moves north, about 14 m a year; it is one of the four lines on the globe that shift with it, with the Antarctic Circle and the two tropics.