Just 7km south of Jokkmokk, the Inlandsbanan finally crosses the Arctic Circle, the imaginary line drawn around the earth at roughly 66°N, which links the northernmost points along which the sun can be seen on the shortest day of the year. Crossing into the Arctic is occasion enough for a bout of whistle-blowing by the train, as it pulls up to allow everyone to take photos. However, the painted white rocks that curve away over the hilly ground here, a crude delineation of the Circle, are completely inaccurate. Due to the earth’s uneven orbit, the line is creeping northwards at a rate of 14–15m every year; the real Arctic Circle is now around 1km further north than this line. It won’t be for another ten to twenty thousand years that the northward movement will stop – by which time the Circle will have reached 68°N – and then start moving slowly south again.
Thanks to the refraction of sunlight in the atmosphere, the midnight sun can also be seen south of the Arctic Circle – Arvidsjaur marks the southernmost point in Sweden where this happens – for a few days each year. The further north you travel, the longer the period when the phenomenon is visible, and conversely the longer the polar winter. True midnight sun occurs when the entire sun is above the horizon at midnight. The following is a list of the main towns and the dates when the midnight sun can be seen; remember, though, that even outside these periods, there is still 24-hour daylight in the north of Sweden in summer, since only part of the sun ever dips below the horizon.
|Arvidsjaur and Haparanda||June 20/21|
|Arjeplog||June 12/13 to July 28/29|
|Jokkmokk||June 8/9 to July 2/3|
|Gällivare||June 4/5 to July 6/7|
|Kiruna||May 28/29 to July 11/12|
|Karesuando||May 26/27 to July 15/16|
|Treriksröset||May 22/23 to July 17/18|