The aurora australis is part of the Antarctic dream for most of us here. Some of the most striking images of Antarctica that I saw before I came down showed the aurora twisting and weaving across the sky in a an palette of vibrant colours. So desperate were we to see the lights that most of the team made a pact at the beginning of winter requesting that we get woken up, whatever the time of night, if even the faintest glow in the night sky was glimpsed by the night-watchman.
However, we were to be disappointed. Our predecessors here, last year’s winterers, saw nothing of the fabled lights and gave well-reasoned scientific arguments as to why we wouldn’t see them either. Even Dave, our resident Polar veteran, had only glimpsed the lights once from Rothera in his many years of coming back here. All of the beautiful images that we’d seen had come from our southerly neighbour, Halley, where the lights are a regular feature of the polar winter.
Without wishing to get too technical, here is a brief explanation of why our odds of seeing the aurora are so slim. The lights (both northern and southern) are generated by an interaction between the solar wind, the stream of particles being kicked out by the sun, and the charged particles in the high atmosphere. These atmospheric ionised particles are concentrated near the poles by the Earth’s magnetic field, which is why the lights are only seen in the north and south where the field is at its strongest.
However, the gradually-moving magnetic South Pole is a long way from the geographic South Pole. In fact, it is currently right over the far side of the continent from Rothera – you can’t get much further away from the magnetic pole than us and still be in Antarctica. It is therefore far more likely that you would see the southern lights in Australia or New Zealand than from here. To put it another way, you have a higher chance of spotting the northern lights from the top of the UK than we have of seeing the southern lights from Rothera, as Scotland is a lot closer to the magnetic north than we are to the magnetic south.
There are a number of other factors as well. The solar wind is only strong enough to have a noticeable effect on the atmosphere when the sun is going through one of its peaks of activity, chucking out lots of material in solar flares. For us to see the lights, one of these peaks of activity has to coincide not only with a rare cloud-free night, but also with one where there is little or no moon, as even a little lunar light is enough to obscure the faint aurora. Not surprisingly, these conditions rarely coincide.
So, with all of this in mind, I felt extremely privileged to catch a glimpse of the lights whilst on my winter trip. They were faint, and just lit up the southern horizon, but they were there. The conditions were perfect – a solar storm coincided with a crystal-clear, moon-free night. What is more, our campsite on the western ice-sheet of Adelaide Island was a long way away from the modest light-pollution produced by Rothera, which is in itself enough to hide the lights from view. Sadly for the rest of the team, the base was shrouded in cloud that night so they saw nothing.
The conclusion of all of this is that I spent an extremely cold evening trying to take long exposures outside, whilst wearing every stitch of clothing I had brought along. And was it worth it? Yes, I wouldn’t have missed it for the world.