The audacious quest to light up the sky with artificial auroras

Karl Lemström trudged down the mountain, frozen and exhausted. It had taken him 4 hours to hike to the summit and several more to defrost and fix his apparatus. It would take another 4 hours to get home on foot through the snow, a gruelling journey he had made every day for nearly a month. But he was a man on a mission, and temperatures far on the wrong side of zero weren’t going to stop him.

He retired to a small shelter he had built from branches at the foot of the mountain, checked his instruments and waited. Soon enough, the needle on his galvanometer twitched. He recorded the reading, went outside, and there it was: a huge shaft of light rising into the sky from the mountain peak.

It was 29 December 1882, and Lemström was in northern Lapland, trying to prove his hypothesis about the origins of the aurora borealis. Not many people believed him, but they would have to eat their words now. He was sure he had just created an artificial version of the northern lights.

Lemström was a Finnish physicist who became obsessed with the aurora borealis at the age of 30, when, as a postdoctoral researcher in Sweden, he joined an 1868 scientific expedition to the Norwegian archipelago of Svalbard, deep within the Arctic circle. He was from southern Finland, so he had seen the aurora borealis before, but not as they appeared this far north. He was captivated.

At that time, the cause of auroras was unknown, and a matter of intense scientific debate. Many of Lemström’s contemporaries had attempted to simulate the phenomenon in miniature, and some apparently succeeded. Around 1860, for example, the Swiss physicist Auguste De la Rive demonstrated an electrical device that produced jets of violet light inside semi-evacuated glass tubes. De la Rive claimed they were “a perfectly faithful representation of what takes place in the aurorae boreales”. (Never mind that their dominant colour is actually green.)

There were two schools of thought about what auroras were. One held that they were meteoric dust attracted by Earth’s magnetic field and burning up in the atmosphere. The other was that they were an electromagnetic phenomenon of some kind, though exactly what was unclear.

Lemström was on team electromagnetism, and he reckoned he had seen the light. He argued that auroras form when electricity in the air flows into the earth at chilly mountaintops. Other aurora researchers thought he was barking up the wrong mountain – or just plain barking. “He was viewed as quite eccentric,” says Fiona Amery, a historian of science at the University of Cambridge who stumbled across Lemström’s largely forgotten work while researching 19th-century aurora science.

Lemström was determined to prove them wrong. Not with a tabletop simulation, but by creating an actual, full-sized aurora in one of its natural habitats, the frigid mountains of Lapland.

By 1871, he was a lecturer at Imperial Alexander University, the predecessor of the University of Helsinki. He persuaded the Finnish Society of Science to back him and mounted an expedition to the Inari region of Finnish Lapland where, on 22 November of that year, he rigged up his apparatus on a mountain called Luosmavaara. It consisted of a 2-square-metre spiral of copper wire held aloft on steel poles about 2 metres tall. Soldered to the wire were a series of metal rods that pointed skywards. He ran another copper wire 4 kilometres down the mountain, to which he attached a galvanometer to measure the current and a metal plate to ground the device. This elaborate apparatus was designed to channel and amplify the electric current that Lemström fervently believed was flowing from the atmosphere into the earth, and hence bring forth an aurora.

Amery says that Lemström saw the aurora as a sister phenomenon to lightning and that his apparatus was analogous to a lightning conductor. “He said lightning is a really sudden emanation. The aurora is very similar, but it’s gradual and kind of diffuse. He thought that you could capture it the same way that you might be able to attract lightning.”

That night, after his freezing trek up and down the mountain, Lemström observed a column of light looming above the peak, and when he measured its spectrum, he found it matched the characteristic yellow-green wavelength of the aurora. He was absolutely convinced that he had called forth an aurora. Unfortunately, with no photographic evidence or independent witnesses, nobody took any notice. “He was quite a fringe character,” says Amery.

And that would have been that, except for a stroke of luck. In 1879, the newly established International Polar Commission announced plans for a year-long jamboree of Arctic science, the International Polar Year. “Suddenly, you could get all of this funding for auroral research,” says Amery. “I think he just managed to be the right person at the right time.”

An arctic mission

Lemström sensed an opportunity and made his way to the planning meeting in St. Petersburg, where he lobbied for the establishment of a meteorological station in Lapland. The commission agreed, and Lemström chose a site near Sodankylä, a small Finnish town inside the Arctic circle. The Finnish Meteorological Observatory was established in September 1882, and Lemström became its first director.

He immediately started scouting for a location to revive his aurora experiments, and hit on a mountain called Orantunturi, about 20 kilometres from the observatory. In early December – a time of year when there are only 3 hours of daylight and temperatures average about -30°C (-22°F) – he and three assistants hiked to the summit and assembled the apparatus. It was a much, much bigger version of the one at Luosmavaara. The copper wreath covered around 900 square metres.

Conditions were gruelling. Lemström later described how it took 4 hours to travel from the observatory to the mountaintop, whereupon he had to defrost and often repair the wires, which kept collapsing and breaking under the weight of hoarfrost. He was able to work for only a few minutes before his hands turned to ice. The apparatus, too, worked only briefly before freezing up again.

But it was worth it. As soon as the apparatus was completed on 5 December, Lemström and his assistants saw what they described as a “yellow-white luminosity around the summit of the mountain, while no such luminosity was observed around any one of the others!” A spectroscopic analysis showed that the light was consistent with a natural aurora.

They saw the same phenomenon almost every night for the next few weeks. The most spectacular display occurred on 29 December, when the shaft of light extended 134 metres into the air. There were no photographs, but Lemström painted a watercolour depicting the beam rising mightily above the mountain peak. He built two smaller aurora conductors on another mountain, Pietarintunturi, and claimed to have witnessed similar phenomena there.

Lemström was now ready to share his success with the world. He despatched a telegram to the Finnish Academy of Science, which shared it widely. In May and June 1883, the journal Nature published three long reports in which Lemström claimed that “the experiments… clearly and undeniably prove that the aurora borealis is an electric phenomenon”.

If he expected the world to fall at his feet, he was sorely disappointed. Even though his expeditions received glowing coverage in newspapers, few of his peers agreed he had produced an aurora. “Some thought he might have created other interesting electrical phenomena like St Elmo’s fire or zodiacal light,” says Amery. “A couple of people thought it might be a strange sort of lightning, almost like ball lightning but in a column. And then some people thought that he was just making it up.”

In early 1884, the Danish aurora expert Sophus Tromholt attempted to reproduce Lemström’s experiment on Mount Esja in Iceland. His device showed “no signs of life whatsoever”. Another replication attempt in the French Pyrenees in 1885 also drew a blank, except for nearly electrocuting its leader, civil engineer Célestin-Xavier Vaussenat.

Undeterred, Lemström pressed on, and again claimed to have created auroras in late 1884. This time, he used stronger wire and added a device to inject electricity into the circuit, which he believed would enhance its powers. Nature again published a report of the expedition, but Lemström’s appetite for working in extreme conditions had waned, and he moved on to pastures new (literally – his next project was on using electricity to stimulate the growth of crops). He died in 1904, convinced to the end that he had created auroras.

He hadn’t. His hypothesis was wrong. The aurora borealis is caused by charged particles entering Earth’s atmosphere from space, not hitting the ground from the air. Nonetheless, Amery says he did create something. She thinks it was probably St Elmo’s fire, a kind of luminous electrical discharge. “That’s my leading theory,” she says. But he probably exaggerated it: “Maybe there was some wishful thinking.” The truth is that we don’t know and probably never will – unless somebody fancies building a giant contraption of copper wire on top of a frigid mountain in the depths of the Arctic winter.