Only three cities sit inside the Arctic Circle
The Arctic Circle is a line drawn on a map, but it is not an arbitrary one. The Earth's axis is tilted 23.4365° from the plane of its orbit, and the Arctic Circle sits at 90 degrees minus that tilt. As of now, 66.5635° N. North of this line there is at least one day a year when the sun never rises at all, and at least one when it never sets.
Sort CouchColumbus's 524-city dictionary by latitude and three cities land above the line.
| City | Latitude | North of the circle | From Seoul |
|---|---|---|---|
| Tromsø (Norway) | 69.6492°N | 343km | 6,772km |
| Murmansk (Russia) | 68.9678°N | 267km | 6,299km |
| Kiruna (Sweden) | 67.8557°N | 144km | 6,828km |
Fourth is Rovaniemi, at 66.5039°. That is 6.6km south of the circle. The town known for Santa Claus misses the line by a hair.
We counted the days the sun stays down
We worked out the sun's declination for each date and checked whether the centre of the sun clears the horizon at local noon. Count the days it does not and you get this.
- Tromsø, 57 days — 23 November to 18 January
- Murmansk, 50 days — 27 November to 15 January
- Kiruna, 36 days — 4 December to 8 January
- Rovaniemi, 0 days
Tromsø and Kiruna are 1.8 degrees of latitude apart, and 21 days apart. The closer you get to the line, the faster the period collapses. Which is how Rovaniemi, 6.6km short, ends up at zero.
This is a geometric calculation based on the centre of the sun. In practice, atmospheric refraction lifts the sun a little, and seeing only the upper rim still counts as sunrise, so the polar night people actually live through is a few days shorter than this. Our numbers do not include refraction.
There are four more bright days than dark ones
Run the same calculation for summer and the sun stays up over Tromsø for 61 days, from 22 May to 21 July. Four more than the 57 lost in winter.
Going by tilt alone the two should match. They do not, because the Earth's orbit is not a circle. The planet is farthest from the sun in early July, and the farther out it is, the slower it moves. So the sun's declination spends 186 days north of the equator and 179 days south — a week's difference. The longer it lingers up north, the longer the sun refuses to set. The bright side comes out slightly ahead.
Seoul to Tromsø is 6,772km, north-northwest. The great circle passes over South Korea → North Korea → China → Russia → Norway. The time difference is 7 hours behind in summer, 8 in winter. Daylight saving moves it by an hour, though what it means to shift the clocks in a city where the sun has not risen for two months is not entirely clear to us.
There is nothing in the south
The Antarctic Circle is at 66.5635° S. The southernmost city in the dictionary is Ushuaia, at 54.8019° S — still 1,308km short of the circle. Below that, not a single city.
The northern polar region has cities in it; the southern one does not. Inside the Arctic Circle is mostly ocean with land wrapped around it, while inside the Antarctic Circle is a continent with no cities on it. The top and bottom of the planet are not symmetrical, so neither is the list.