The Northern Lights, page 6
On 11 January the honeymoon came to an abrupt end. Cirrus clouds appeared during the afternoon and rapidly built up into a huge bank, the length of the eastern horizon. Hætta, who had delivered the post that morning and stayed for lunch, took one look at the sky and rushed to harness the reindeer. The animals were skittish, nipping each other and chewing at their tethers, sensing the need to find shelter from the coming storm. Hætta gathered the reins into his hands and the animals careered down the hill before a command was out of his mouth. Boye nailed planks to the outside of the windows and let loose the reindeer to fend for itself, making sure its bell was firmly attached, in the hope of finding it again once the storm had passed. He brought in all the food he could carry from the larder and stacked it in the vestibule. Knudsen climbed onto the roof to dismantle the instruments, leaving only the strongest anemometer to measure the wind speeds. Birkeland called Sæland to warn him of the approaching weather.
Within an hour of Hætta’s departure the wind on the summit was too strong to stand in. The men inside the observatory grew tense as the screaming air ripped at the boards on the windows, forcing its way around the frames and under doors. Despite the sturdiness of the building, they felt small and vulnerable in comparison with the might and ferocity of the hurricane outside. It was like being in a tiny fishing boat facing towering waves. They had to raise their voices to make themselves heard and lean against the stove to keep warm in the drafty building. The candles in the lanterns were blown out so frequently that Boye filled the paraffin lamps instead— no one liked the smell but they were less easily extinguished. Despite Boye’s best efforts to seal the outside door, the wind and snow forced their way inside. The floor of the tower was covered in powdery snow, which formed small drifts in the corners as well as around the drums of oil and paraffin. Every hour Birkeland put on his reindeer jacket and left the kitchen to check that the magnetometer recordings had not been disrupted by the sudden gusts of wind that blew under the doors. With such events outside, Birkeland expected to see the magnetometers in motion, but the beam of light shining on the photographic paper was as straight as a ruler, an instance of serenity amid chaos. By eight o’clock the phone line to Talvik peak was severed and the group in the main observatory prayed Sæland would be all right; memories of Hansen’s mutilated hands were still fresh in their minds. The Talvik observatory was less substantial than their own, and without the phone Sæland would be utterly alone.
The three men went to bed but no one slept. The thick walls shook with the blasts and the timbers in the roof made alarming snapping sounds. The steel guy ropes holding the roof to the house strained in the heaviest gusts; the men were aware that, if the ropes snapped, their shelter would be sucked into the storm as if it were made of straw. A plank was ripped from the window between the bunks and there was an immediate increase in the freezing air forcing its way through the frame and into their beds. Boye nailed a reindeer skin over the window, but it had little effect. Around midnight one of the guy ropes snapped and ricocheted against the building, and the men listened in fear to hear if the others would follow suit. They held. After a while exhaustion lulled the men into fitful sleep until three in the morning when the outside door burst open and a jet of wind, ice, and snow overwhelmed the tower and slammed the kitchen door back against the wall. Papers, pans, books, lamps, crockery, and chairs were hurled around the room by the spiteful blast. Dressed only in woolen pajamas, Knudsen tried to push the door closed, but twice it was blown from his hands and thrown back against the wall. Boye went to his aid, crawling across the floor, but even together they could not force it shut against the wind. Only with the combined strength of all three men was it eventually closed and nailed shut. With their escape route thus blocked, Birkeland feared they could burn to death as the winds gusting down the chimney forced smoke and hot ash into the room.
The savage storm blew for twenty-one days without a break. They were completely cut off from the outside world, from newspapers, post, people, doctors, food, and fuel, even from the landscape; all that existed was the weather. The group became disoriented at first: with the windows boarded up and the storm obscuring the twilight of midday, there was nothing to indicate the passage of time. On the fourth day, during a brief lull in the storm and desperate to leave the cramped observatory, they launched one of the kites for taking measurements of air electricity and wind velocities at high altitudes. The wind gusted and the kite dragged Boye to the edge of the cliff until he was forced to let it go. The three men watched in dismay as the small point of white was swallowed by the mass of dark, scudding clouds and was lost forever.
They seized any moments of relative calm to climb onto the roof to repair the anemometer or note the outdoor temperatures. Birkeland decided that a second ethanol thermometer and anemometer should be placed away from the shelter of the observatory to obtain truer readings. While Knudsen was attempting this task, a sudden squall hit the summit and he was blown down the steep incline by the cable car into deep snow forty meters below. Boye crawled to the observatory and called to Birkeland for help. The professor roped himself to the ring by the door and Boye clung to him as the gale, with renewed force, tore at their hair and Birkeland’s glasses. Knudsen would die of exposure if they did not find him quickly. When they reached the cable car, Boye tied himself to the metal struts, but before he could descend a gloved hand came over the lip of the slope and grabbed at his foot. Boye and Birkeland dragged Knudsen over the edge, put his arms round their shoulders, and helped him back to the hut. Birkeland broke the ice on a bucket of water and pushed Knudsen’s hands into it. His eyes were half-shut, his face white with frostbite and his lips a purple blue. They sat him next to the fire, standing beside him to keep him upright. Knudsen had fallen only a few meters onto a narrow ledge and was bruised and winded but nothing seemed broken and the frostbite soon receded. They decided that the next time anyone ventured outside they would rope themselves to a metal ring that had been set into the wall beside the entrance by the builders, who knew better than Birkeland how violent the weather could be.
The wind on the summit seemed to defy all the natural laws they had ever observed. At times, the storm grew so violent that the men were afraid the little building would lose its battle and be hurtled from the summit into the jaws of the valley below. Enormous snowdrifts that threatened to block the door or chimney would be blasted away in hours when the wind changed direction. The lack of sunlight and the claustrophobic effect of being trapped in the dark hut began to exert a depressive influence. There seemed little they could do and conversation began to lag.
“You need a sanguine temper to be a physicist,” Birkeland reminded them when the difficulties imposed on their work by the extreme weather led to frustration and bad moods. Despite his brave words, the strain was beginning to show on him too. Pressure from the government combined with his own high hopes stopped him sleeping. During the first week of confinement he worked through the night with the 250 rolls of automatic readings from the magnetometers that had been amassed since 1 November. They were the shadows of invisible forces raging overhead, and they allowed Birkeland to see what was happening to the magnetic field above their observatory. As the lines on the rolls wavered, they revealed when the field increased or decreased, turned east or west. In this way, Birkeland was soon able to build up an accurate picture of how the magnetic field changed during the course of a day, a month, two months. Studying the magnetograms with his understanding of Maxwell’s electromagnetic equations and other experiments by Ørsted and Ampère, Birkeland became convinced that the magnetic disturbances were caused by electric currents in the atmosphere, although he was still not sure where these massive currents came from. Was it something limited entirely to the Earth, like a form of lightning, or was it something entering the Earth’s atmosphere from space, a cosmic force? He worked feverishly, often all night, sensing he was on the edge of a breakthrough.
He roused the others from their torpor and set them the task of creating small maps out of the recordings and equations. Boye, who could draw well, was in charge of tracing the outline of Finnmark over which Knudsen and Birkeland would mark arrows of different lengths to represent the direction and strength of the magnetic storms above their heads. As currents were known to run at right angles to the magnetic field, Birkeland’s assistants were also able to plot the direction and strength of the electric currents that were causing the storms. The field was usually quiet until about six o’clock in the evening when the first small variations in the recording line appeared. On some days there was no variation at all, but on others the line began to veer a great deal across the page, creating peaks and troughs that mirrored the changes in the field. Birkeland quickly confirmed the reports of earlier observers that the auroras appeared only during magnetic disturbances.
In many ways it was satisfying that the storm outside seemed a permanent accompaniment to the storms the men were plotting. Had the weather been better, perhaps they would not have spent such an intensive period thinking and analyzing results. Night after night Birkeland would sit up and furiously scribble equations. On 17 January the men recorded in the ledgers that the sun had returned—according to their charts it would rise over the mountains that day for six minutes—but the weather was too bad to risk opening the door to see if there was any perceptible change. It seemed unlikely that it could shine through the dense, swirling snow that wrapped itself around the summit like a snake around its prey.
Once Birkeland had firmly established that auroras did not appear without magnetic disturbances, he turned his attention to what caused these storms. The beginnings of a theory had occurred to him as early as 1896, and an extraordinary event two years later had led him to write about his ideas in the newspaper Verdens Gang. On 9 September 1898 a huge auroral storm could be seen in startling red and brilliant orange over the skies of Europe as far south as London, Paris, Vienna, and Rome. As in previous centuries, the red auroras were popularly interpreted as portents of war, famine, and strife. Many scientists, including Birkeland, scoffed at the notion that they were a celestial warning, but as the Lights evaporated in the dawn of 10 September, a horrifying tragedy rocked Europe and echoed across the world in thousands of telegraph wires and newspaper headlines. An Italian anarchist, Luigi Luccheni, assassinated the empress of Austria and Hungary, once regarded as the most beautiful princess in Europe and much loved for her charitable work. She was stabbed in the chest with a stiletto knife.
Because auroras occurred in southern Europe only a few times in a decade, to see an extraordinary red light on the eve of an assassination caused many to believe that the scientists were wrong and that the Lights were indeed some form of message. Birkeland, however, considered the tragedy to be an unfortunate coincidence—unfortunate indeed for the empress and her family but also for a scientific explanation of the auroras. He started to research what was known about auroras and read that they frequently coincided with the appearance of sunspots. He had immediately sent a telegram to an acquaintance, the famous Parisian astronomer Camille Flammarion, at the Paris Observatoire, requesting information about sunspot activity around the time of the assassination. Flammarion had confirmed that there were several unusually large sunspot groups passing the sun’s meridian three days before the massive auroras were seen over Europe.
The connection between sunspots and auroras was mentioned by Birkeland in the article he wrote following the assassination, entitled “A Message from the Sun.” The title was a direct reference to Galileo’s Starry Messenger, published in 1610, in which the famous astronomer promoted the heliocentric concept of the solar system first suggested by Nicolaus Copernicus a hundred years earlier. In this system, the sun, and not the Earth, was at the center of the solar system, and Birkeland believed the sun’s importance in the phenomenon of the aurora was greater than anyone had so far imagined. Sunspots were not the only event on the sun related to auroras. In 1859 Sir Richard Carrington of the Kew Observatory was the first to observe a flare coming from the sun—“two patches of intensely bright and white light broke out.” He noted that this “conflagration” was followed eighteen hours later by a great magnetic storm that disrupted telegraphic communications and coincided with tremendous auroras seen in Hawaii, Jamaica, Chile, and Australia. Despite this seemingly direct correlation, Carrington “would not have us suppose that he even leans towards hastily connecting” these events; “one swallow does not make a summer.” Many scientists dismissed the connection between activity on the sun and auroras because there were often sunspots without auroras, or vice versa, and because they did not believe that charged particles could reach the Earth from such a distance. Birkeland, however, was becoming more and more convinced of a solar-terrestrial relationship.
Stranded in the darkness on the mountain in howling gales, Birkeland thought continuously upon the connection between sunspots and the auroras. The sun had been systematically studied in Europe since 1610, when Galileo trained his telescope on it and first noted that the glorious golden orb was, in fact, spotty. In 1843 a German pharmacist and amateur astronomer, Heinrich Schwabe, showed that the sun was not constant in its activity, that it passed through an eleven-year cycle. For many years he had studied the number of sunspots on the face of the sun and realized that their number increased for just over five years then decreased for another five or so. When Captain Lange mentioned that the incidence of auroras had been lessening in recent years, Birkeland had been delighted because he knew the year 1900 was at the least active part of the sun’s cycle, resulting in fewer auroras to watch. This was useful for his research because too many or too complicated auroras would be hard to decipher and render repeating patterns difficult to discern.
Birkeland had brought with him the available records of auroral displays. These were nowhere near as complete as the sunspot records, the Lights being a more elusive phenomenon and a greater challenge to study, but there were some useful observations—particularly from the Polar Year 1882–3, the first international attempt to obtain regular observations of the Lights and related magnetic disturbances. For many nights Birkeland pored over these books and his own results, comparing all the work that previous scientists had done with his own observations, puzzling over the connection and the imperfect coincidences among the sunspots, the magnetic field, and the auroras. He remembered his days in Paris when he had worked on Maxwell’s equations with the eminent Professor Henri Poincaré, Birkeland’s mentor, who was greatly admired for his advanced understanding of mathematics, physics, mechanics, and astronomy and his philosophical and popular expositions on science. He thought of Quale’s hydroelectric power station and of electric currents until he became so tired that the elements of his past melded into one. Without warning, one evening suddenly the muddle cleared and the pieces came together to form a solution.
He became convinced that his initial hunch was correct: the force disturbing the magnetic field came directly from the sun in narrow beams of electrically charged particles called cathode rays. Cathode rays were first noticed at the end of the 1860s when mercury pumps were developed that were able to create vacuums in glass tubes. Experiments with electric currents in these vacuum tubes revealed that, under certain circumstances, they produced glowing rays. In 1876 the German physicist Eugen Goldstein named the rays after the cathode, the negative terminal in the tube, from which they appeared to be emitting, although it was not understood how or why these rays were formed. Only in 1897 did the British scientist J. J. Thompson show that cathode rays consisted of high-velocity streams of negatively charged particles: electrons. Birkeland was sure that the sun emitted similar beams that were narrow and focused and often missed the Earth completely, which was why sunspots did not always result in auroras. Birkeland surmised that sometimes these active particles hit the magnetic field of the Earth and followed the field lines down toward the poles, where they struck atoms in the atmosphere and the energy created by the collisions was emitted as light—the Northern Lights. That explained why they appeared only during magnetic storms: the cathode rays from the sun were moving beams of electrons that created electric currents; these, in turn, made their own magnetic fields, which were recorded by the magnetometers. These same beams of charged particles, on reaching the upper levels of the atmosphere, created the auroras. Birkeland never gained any significant readings of air electricity near the ground because the force that disrupted the magnetic field did not come from Earth, as so many scientists believed, but from space, from the sun. His theory also explained why on one or two occasions that winter, similar auroras appeared at twenty-seven-day intervals: the sunspots took twenty-seven days to make a complete circuit of the sun and often made two or three circuits before disappearing. In effect, the sun was creating the magnetic storms and was the original source of the auroras.
