All you need to know about the Northern Lights

Please see a list of the most asked questions and answers about the Northern Lights

When is the best time to see the Northern Lights?

You can only see the northern lights when the sky is dark. During the light nights of the Arctic summer, the aurora may be active - but it won't be visible because the light emitted by the aurora is much weaker than sunlight.

The best time to see the northern lights is when the sky is clear of any clouds. Some people claim the aurora comes out when temperatures are colder. This isn't the case - it's just that when the skies are cloudless, temperatures tend to drop.

The northern lights are most commonly seen between 17:00 and 02:00. They don't usually exhibit for long - they may only show for a few minutes, then glide away before returning. A good display may last for no longer than a quarter or half an hour, though, if you're really lucky, it could extend to a couple of hours or longer.

The aurora is at its most active around the equinoxes - that's to say, in March and September. The end of August and early September are good times to travel if you're a keen hiker, yet still want to try your luck with the lights - at this time of year the snow hasn't fallen, but the night-time skies are dark.

The northern lights become more active and intense around the peak of a sunspot cycle, and in the three to four years immediately following the peak.

The waxing and waning of the moon makes no difference to the northern lights. While a full moon lightens the sky, and may therefore reduce the visual intensity of a display, the northern lights can be seen at all stages of the moon's cycle. In fact, seeing the Northern Lights behind a full moon is quite a spectacular sight.

What are the Polar Nights?

The Arctic Circle sits at 66°33'N. At this point of latitude the sun doesn't rise on the day of the winter solstice (and doesn't set at the summer solstice), though, as the sun is hovering just below the horizon, the Arctic Circle never goes completely dark - there's always a bit of dusky twilight. The further north into the Arctic Circle you go, the longer the periods of winter darkness.

What should I wear?

With the right clothing, the Arctic winter can be surprisingly comfortable. Many local suppliers will lend or rent you the thick outer garments that are expensive to buy. If your holiday consists of organised excursions such as northern lights viewing plus short dog sledging and snowmobile trips, good-quality ski clothing should see you through (tip - check out summer sales in the UK for bargains on winter clothing, especially those marked 'thermal'). However, if you're going to be spending extended periods outdoors in sub-Arctic and Arctic weather, you should upgrade to a higher level of protection.

The Layer Principle

It is much better to wear a number of thin layers than just a few thick ones. The air trapped in between thin layers warms to your body's temperature and acts as valuable insulation. Make sure your clothes fit well and that some of your layers are of differing sizes to avoid constriction, which will prevent air circulation and will be uncomfortable.

Underlayers

In cold conditions, it's better to wear wool, silk or synthetic polypropylene next to your skin. Avoid cotton: when you sweat, it gets cold and clammy, and doesn't dry out easily. Merino wool is excellent. On top of your base layer, you'll need to wear at least two or three additional layers, which should be made of fleece or wool. Remember that you'll need long johns as well as upper-body protection.

Outerlayers

A well-insulated jacket is a must, as are insulated trousers or salopettes in cold conditions. If the weather is likely to be wet you'll need waterproofs; don't take unwaterproofed down out in the rain as it soon becomes soggy and useless. Some local suppliers such as snowmobile operators will loan one-piece thermal suits to put on over your jacket and trousers.

Gloves

In very cold weather, it's a good idea to wear two pairs of gloves - one thick pair of mitts (mitts that don't separate the fingers keep your hands warmer) and a thin pair of gloves underneath that allow you the use of your fingers when you need to do something fiddly, yet ward off the icy cold for a short time, at least. If you're prone to cold extremities, you can buy carbon hand-and foot-warmers from most good outdoor shops. Shake these up to activate them, pop them into your glove or boot, and they stay warm for around eight hours. If you're going to stay outdoors for an extended period, pack a spare pair of gloves - if you lose one in cold temperatures you'll soon freeze your fingers.

Footwear

You'll need proper winter boots if you're going to be outside for extended periods. Many local suppliers will provide these - make sure you request a size larger than you normally wear, to comfortably accommodate extra pairs of socks. Hiking style winter boots are suitable for simple excursions such as northern lights viewing and town-based activities, but they're not advisable for more adventurous snow based activity as snow can easily get inside them. Make sure your footwear has good grip for walking on snow and ice.

Socks

These should be made of wool, never cotton. Pack an extra pair or two in your rucksack if you're going out snowmobiling or dog sledging - if your feet become damp or wet you should change into dry socks: wet feet soon become frostbitten feet.

Hats and headwear

Take a woollen or fleece hat which covers the ears, as well as a balaclava, Buff or face mask to cover mouth, nose and cheeks. Noses and cheeks are especially prone to frostbite, and should be kept covered whenever possible - skin can freeze in minutes in very cold weather.

Eyewear

You may need sunglasses or tinted goggles as the sun on the snow can be dazzling. Contact-lens wearers may find the cold and dryness makes lens-wearing uncomfortable and should pack glasses as an alternative.

Swimwear

If you intend to use any sauna facilities, you may want to pack a swimsuit - unless you're brave enough to go 'au naturel'. There may be occasions too when you'll find yourself in an outdoor hot tub watching the northern lights overhead.

Cosmetics

The northern air is very dry, and you'll need to pack plenty of lip salve. Some people have problems with water-based moisturisers. Specialist products are available - ask your local chemist.

What temperatures should I expect?

To give you an idea of the temperatures you'll face whilst in search of the northern lights, the average daily temperatures in degrees Celsius are listed below for Tromso. Remember, wind-chill factor can reduce these figures.

Tromso Sep 6.9°C / Oct 2.7°C / Nov -1.2°C / Dec -3.4°C / Jan -4.4°C / Feb -4.3°C / Mar -2.8°C

Frostbite

This occurs when the skin and underlying tissue freeze due to extended exposure to very low temperatures. It can affect any part of your body, but the extremities, such as the hands, feet, ears, nose and lips, are most likely to be affected. However, with the right clothing and sensible precautions frostbite can be avoided.

How do I photograph the Northern Lights?

With compact cameras, photographing the northern lights is often a matter of luck, although a night-time setting sometimes helps. Capturing that perfect shot can be surprisingly easy, however, if you use an SLR camera that allows long exposures of 10 to 20 seconds together with a tripod.

For the best results you'll also want a lens with a wide aperture (f2.8 is good enough, f2.4 is better and f1.4 is best) and a wide angle. Experienced northern lights photographers often wrap foam around their tripod's legs to prevent them-selves from touching the metal with bare fingers (the skin sticks). Many photographers prefer to use a cable release - but just pressing the button can also work well. It's also a good idea to wear a thin pair of gloves to protect your skin from frostbite - but remember the protection thin gloves offer will last only a few minutes in cold conditions. Carry thick mitts, too. Plus, you'll need to take a headlamp so you can see what you're doing in the dark.

Camera batteries die fast in cold temperatures. Always carry a spare, and keep it tucked into your clothing, close to your skin to keep it warm. Even better, buy a battery grip (they cost from about £100) and load it with lithium AA batteries - these keep their charge for a reasonable period. Try not to take your camera indoors with you as the lens will fog up with the change in temperature and, when you go outside again, the condensation will turn to ice. If you must take your camera indoors, put it in a plastic bag - ziplock seals work well.

When selecting a location for your photography, try to find a place with some foreground - a tent or building lit from the inside, or some trees - that will give your pictures perspective. For the best outcome, an ISO of 400 is probably best; go up to 800 and the photos can be noisy. Set the focus to infinity and open up the aperture as wide as your lens will allow. If you can, turn off the LCD display as its light will interfere with your vision through the viewfinder in the dark. Then just point and shoot and pray.

One last word: unless you have a fisheye lens, your camera will only capture a fragment of the sky, and during a really spectacular display, the northern lights work their magic across 360°. It's easy to get carried away with photography - but for the best experience, remember to take a few moments just to step back and enjoy the show.

Film Cameras

Old-fashioned film cameras can work well in cold temperatures as they are not as reliant on battery power as their digital replacements. Be careful when winding on film, however - in cold weather it can become brittle and break. Changing film, too, can be tricky with cold, glove-clad hands. It can also be difficult to develop film to reproduce the colour of the northern lights correctly. Often they appear far greener in photographs than they do to the eye.

Making Movies

It is virtually impossible to film the northern lights using a regular movie recorder. To record moving images of the northern lights, expensive specialist equipment is required.

How will I know if the Northern Lights will appear?

There is never a guarantee of spotting the northern lights, but northern lights forecasting is generally accurate - it's much more reliable than the weather forecast. The forecast corresponds to the planetary magnetic index (Kp) on a scale of one to nine, with one being very low activity and nine very high. The Geophysical Institute at the University of Alaska has an excellent website (www.gi.alaska.edu/AuroraForecast/Europe/), which allows you to view predicted activity in all auroral regions. You can also sign up for northern lights forecast email alerts that tell you when activity rises above four to five on the Kp scale. There are also many other sites that help to predict and forecast the northern lights or the aurora borealis.