Published online 28 February 2008 | Nature | doi:10.1038/news.2008.631

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Aurora observatory opens on remote Arctic island.

Eyes on the sky: the Svalbard observatory is ideally placed to watch the aurora. M. Hopkin / Nature

SVALBARD For many people, living through the murky twilight of a polar winter would be a depressing experience. But not for the scientists working at a new observatory on the remote Norwegian island of Svalbard. For them, the Arctic darkness gives them the perfect view of the aurora borealis, also known as the northern lights.

These mysterious swirls of light, visible in the polar sky, are caused when superfast particles spat out by the Sun's nuclear inferno hit our atmosphere, causing atoms high in the sky to give off a ghostly glow. These aurorae are only visible in polar regions because the Sun's particles are channelled along the Earth's magnetic field lines, which emerge roughly from Earth's poles. Because they occur at altitudes of more than 80 kilometres, studying them requires very sensitive optical instruments, and a decent vantage-point far from any light pollution.

The new Kjell Henriksen Observatory, perched at the top of the Advent Valley outside Svalbard's largest settlement, Longyearbyen, offers just that. Svalbard provides "a window into space", says Fred Sigernes, an atmospheric researcher at the University Centre in Svalbard, which runs the new observatory. It joins several other facilities that already study the northern lights.

Opened last week by Norway's higher-education minister, Tora Aasland, the new observatory currently houses instruments from 16 institutions in 7 countries. "There are facilities for all sorts of people and instruments," says Dag Lorentzen, also from the University Centren in Svalbard. The instruments are mainly optical, because the aurora borealis gives off visible light.

The observatory will be one of the few places on Svalbard that will be at its busiest during the winter months, says Lorentzen. Though some work has already begun, the main optical telescope will be installed this summer; so the real action will begin next winter, when researchers will be observing the dark skies around the clock.

Northern dark

From late October onwards, Svalbard, at a latitude of about 78º North, is plunged into round-the-clock darkness. Now, in late February, it is only two weeks since the official 'polar dawn', and by mid-morning still only the mountaintops are tinged with the Sun's tentative pinkish rays. Down in Longyearbyen, the light, reflected off the snowy slopes, has an eerie bluish tinge — the town will not see direct sunlight for a few days yet.

The researchers at the observatory have a fairly unorthodox commute to work. The journey from Longyearbyen involves driving along the wide glacial Advent Valley to Mine no. 7 — Svalbard's only still-functioning coal mine. From there, the observatory is reached in army-surplus vehicles, which bump and rumble up the frozen slopes on caterpillar treads.

So sensitive are the instruments at the observatory that visitors are not even allowed to use headlights when driving up the hillside, and all communal areas within the observatory have heavy shutters on their windows.

Once at the observatory, access to the building is currently through the back door, as the main entrance is under 2 metres of snow. But they're prepared for poor weather. They have 10 tonnes of backup batteries for power emergencies, and several rooms full of bunk beds for sleeping in the event of storms. Lorentzen and his colleagues have already done an 18-day stint at the observatory, while waiting for the right conditions to launch a radar rocket into the atmosphere to collect data on the chemicals given off when the aurora lights are produced.

On the day side

Ironically, Svalbard's long polar night will also allow researchers to study what are often referred to as the 'dayside aurora'. The most commonly visible northern lights are the 'nightside aurora', which occur when solar-wind particles are 'slingshotted' around by Earth's magnetic field and enter the atmosphere on the side of Earth facing away from the Sun. That's why northern lights are typically visible at night.

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But during the noon darkness of Svalbard's winter, observers should be able to see the dayside aurora, which enter our atmosphere directly. Without the extra slingshot magnetic kick, these particles are less energetic, so produce a fainter, reddish glow.

The observatory's researchers hope that their data could soon help to answer more general questions about solar weather, of which the northern lights are just one side-effect. Large solar storms, which produce spectacular auroral displays, can also knock out communications satellites, force planes to be diverted, and mess up your in-car global positioning system. The Sun is currently in the weakest phase of its 11-year activity cycle — within a few years, such solar flare-ups are set to become more common.

It may even be possible, one day, to harvest the immense energy outbursts behind the northern lights, Lorentzen says, although he admits that currently we have no idea how. "All we know is that it is a lot of energy," he says.