Tromsø, the city that studies its own sky

For most visitors, Tromsø is the last proper town before the map turns mostly white, and the place a cruise pauses in the hope that the sky will do something. For much of the last century it has also been where scientists came to find out what that something actually was. The Norwegian physicist Kristian Birkeland worked out, in the early twentieth century, that the aurora was caused by charged particles from the sun following the earth's magnetic field into the upper atmosphere, and he did a good deal of that work from stations in the far north of Norway, in conditions not far removed from what a passenger on deck experiences today.

Birkeland's method, when the theory was still contested, was to build a scale model in his laboratory: a magnetised sphere, standing in for the earth, bombarded with charged particles in a vacuum chamber, glowing at its poles in miniature rings that looked, to anyone who saw them, unmistakably like the aurora itself. It took decades and the arrival of actual satellites for the wider scientific community to accept that he had been right, which is a fairly Norwegian sort of vindication: slow, unglamorous and eventually undeniable.

A university town with an unusual specialism

Tromsø's Geophysical Institute has been observing and recording the aurora since the 1920s, one of the longest continuous records of its kind anywhere, and the city's university, founded in 1972, still has a strong line in space physics as a direct result. None of this is dressed up for tourists particularly; it is simply what the place has been doing, methodically, for a hundred years, in the same skies that cruise passengers now watch from a rather warmer vantage point than Birkeland had. The institute's older instruments and the story behind them are held partly at the university's own museum, a modest counterweight to the aurora tours that now make up a good share of the city's winter economy.

Fish, furs and, eventually, physics

Before the science, Tromsø was a trading post and, from the nineteenth century, a base for Arctic hunting and fishing expeditions; ships heading for Svalbard and the polar pack ice provisioned here, and the harbour still has some of that working character. The Arctic Cathedral, its best-known modern building, is glass and concrete rather than stone, built in 1965, and it says something about the town that its most photographed landmark is barely older than the aurora research it sits a short walk from.

That mix of old trade and new science is still visible walking from the harbour up into the town centre: wooden warehouses that once handled furs and dried fish stand within a few streets of laboratories and lecture halls, with nothing in the layout suggesting the two were ever considered separate parts of the same economy. Tromsø has never really had the luxury of choosing one identity over the other.

Watching from a ship rather than a station

A cruise calling at Tromsø has the practical advantage Birkeland's generation didn't: it can move. A ship working its way along this stretch of coast, spending several nights at sea rather than one, can put distance between itself and cloud in a way a fixed observatory never could, which does genuinely improve the odds of a clear window somewhere along the route. It remains a matter of odds, not certainty; nobody, in a century of watching, has worked out how to make the display appear on demand.

What's worth going for regardless

Even on a cloudy night, Tromsø by winter is worth the detour: a working Arctic town, a serious university, and a harbour with more going on than the tourist season alone would explain. Arthur would rather send you somewhere with its own reasons to exist than somewhere that depends entirely on the sky performing.

Dress for real cold rather than a brisk British winter; temperatures well below freezing are ordinary here from December through February, and any evening spent hoping for a display means standing still outdoors for longer than walking around would ever require. A flask, a proper coat and low expectations, oddly, tend to produce the best evenings, whatever the sky decides to do with them.