On and above the Arctic Circle, an imaginary line drawn round the earth at latitude 66.5 degrees north, there is a period around midsummer during which the sun never makes it below the horizon, even at midnight – hence the midnight sun. On the Arctic Circle itself, this only happens on one night of the year – at the summer solstice – but the further north you go, the greater the number of nights without darkness: in Bodø, it’s from the first week of June to early July; in Tromsø from late May to late July; in Alta, from the third week in May to the end of July; in Hammerfest, mid-May to late July; and in Nordkapp, early May to the end of July. Obviously, the midnight sun is best experienced on a clear night, but fog or cloud can turn the sun into a glowing, red ball – a spectacle that can be wonderful but also strangely uncanny. All the region’s tourist offices have the exact dates of the midnight sun, though note that these are calculated at sea level; climb up a hill and you can extend the dates by a day or two. The converse of all this is the polar night, a period of constant darkness either side of the winter solstice; again the further north of the Arctic Circle you are, the longer this lasts.
The Arctic Circle also marks the typical southern limit of the northern lights, or aurora borealis, though this extraordinary phenomenon has been seen as far south as latitude 40 degrees north – roughly the position of New York or Ankara. Caused by the bombardment of the atmosphere by electrons, carried away from the sun by the solar wind, the northern lights take various forms and are highly mobile – either flickering in one spot or travelling across the sky. At relatively low latitudes hereabouts, the aurora is tilted at an angle and is often coloured red – the sagas tell of Vikings being half scared to death by them – but nearer the pole, they hang like gigantic luminous curtains, often tinted greenish blue. Naturally enough, there’s no predicting when the northern lights will occur. They are most likely to come out during the darkest period (between November and February) – though they can be seen as early as late August and as late as mid-April. On a clear night the fiery ribbons can be strangely humbling.