Observing the Aurora
The Aurora, or Northern (or Southern) Lights is one of the most spectacular sights you can ever see. Viewing the aurora depends on having clear skies, but unlike the eclipse, the aurora can be seen on many nights during the year.
Observing the Aurora
Aurorae tend to occur near the Earth’s N and S magnetic poles, and therefore they are best seen in fairly high latitudes, although really strong displays have been seen as far South as the Mediterranean and the USA, although that is rare. So the Faroes are well placed to see any aurorae which may occur.
Unlike eclipses they are not really predictable in advance, although sometimes we get a few days warning that one is likely, though not certain. And they may also vary in strength and intensity, from weak glows low in the sky to an amazing dancing display of streamers and curtains and arcs of multicoloured lights filling the sky which will simply leave you gasping in amazement.
They are caused when electrically charged particles emitted by explosions on the Sun travel through space and happen to collide with Earth. When this happens, they get trapped in Earth’s magnetic field and get drawn down to our N and S magnetic poles. They then interact with different atoms high in our atmosphere causing them to glow in different colours. But they don’t concentrate at the Poles themselves, but instead form a slightly elongated oval around the magnetic poles.
Note also that the magnetic poles don’t coincide with the geographic poles, and they also wander around slowly, but that need not concern us at the moment.
So how do we know if an aurora is likely on any night? Firstly, we don’t know in advance when the Sun is going to emit a Solar Flare, or a Coronal Mass Ejection (CME), and we won’t know if any that do happen will be aimed at Earth, although once they happen we have a fair idea. But we also don’t know how long such a CME will take to travel the 150 million Km across space from Sun to Earth, as the speed of each one can vary quite considerably, and we can’t see them once they leave the vicinity of the Sun until they arrive here, or not.
So we don’t know if they will hit Earth at all or not, and we don’t know whether they will arrive in our night-time, or in our daytime when we can’t see them.
Further, we don’t know in advance what the magnetic polarity of each CME will be, and for the best aurorae here we need them to have negative polarity.
But prediction tricks and information are improving all the time, so we usually have a fair idea about a day in advance. And in any vase, at high latitudes like the Faeroes, there is a chance of at least some auroral activity on most nights, and it’s best seen when there is no moonlight, which of course happens at the time of a solar eclipse!
To photograph the aurora you should have a camera which can give longish exposures, say 10 to 30 seconds, or at least have a ‘night scene’ setting. You will also need a tripod, even a small light one will suffice. It will also need to focus on infinity during the exposure. The wider the angle, (or shorter focal length) of the lens, the better. For video imaging, which will show the movement of the patterns of light, you will need all the above, plus a good low light performance, i.e. a high ISO number available.
Terry Moseley, 2015