The Northern Lights or Aurora Borealis is a natural phenomenon that can paint the night sky with unearthly, surreal color. The Southern Lights or Aurora Australis also exist but are not as often observed.
The Aurorae are caused by charged particles ejected from the sun. When these particles reach the earth, they collide with gas atoms in the earth's atmosphere energising those atoms and creating a spectacular multi-coloured light show. Charged particles are affected by magnetic fields, so the Lights occur mainly at far Northern or Southern latitudes near the Earth's magnetic poles.
The Lights are generally fairly dim, but sometimes bright enough that reading a newspaper on a moonless night is possible. Both brightness and how far South they are visible vary according to three factors: time of year, an 11-year cycle in solar activity, and solar storms. These are discussed in more detail later.
To observers at far-northern latitudes, the Lights are a frequent occurrence, but many who live in more temperate climates have never seen them, even though they are occasionally seen as far South as 35 degrees North latitude. This article will help you improve your chances of seeing the Lights if you journey North.
Light pollution around cities can mask a dim aurora display. Therefore, areas at least 30 km from cities are preferred for viewing. The trick is to get far enough from cities for good viewing (generally easy, since most Northern areas are not heavily populated) without taking undue risks in a climate that can easily kill you.
The Northern Lights look somewhat similar to a sunset in the sky at night, but appear occasionally in arcs or spirals usually following the earth's magnetic field. They fairly often look like moving curtains of light, high in the sky. They are most often light green in color but often have a hint of pink. Strong eruptions also have violet and white colors. Red northern lights are rare, but can sometimes be observed at lower latitudes.
Contrary to intuition, seeing the Northern Lights isn't just a matter of heading North. The Lights occur mainly in a circular or elliptical band centered on the earth's North Magnetic Pole, which is not at the same location as the North Geographic Pole, but rather is offset in the direction of northern Canada. Furthermore, auroral displays aren't strongest at the pole; the band of greatest activity is offset from the Magnetic Pole by 20 degrees or so; the magnetic lines of force are curved and the curvature creates the offset.
The Northern Lights oval, meaning the area with the highest probability of seeing the Lights, covers most of Alaska, northern parts of Canada, the southern half of Greenland, Iceland and Northern Norway and the northernmost areas of Sweden and Finland, as well as the western half of the Russian north. There is a similar oval in the South; see the photo.
Regions such as central and southern Scandinavia, the north-central United States and Scotland also frequently see Northern Lights, but not as often as directly under the Northern Lights oval. Svalbard sees less Northern Lights than Northern Scandinavia, but is a place to observe the fainter Day Northern Lights during its long Polar night.
The exact location of the North Magnetic Pole varies from year to year, sometimes by tens of miles. The Pole has been moving north for a few years and is now near Ellesmere Island in the nearly uninhabited far north of Canada. As a consequence, the advantages of being on the "right side" of the earth are not as pronounced as they were some years ago. Still, there's a slight North American bias even today in your chance of seeing the Lights.
That said, the actual latitudes of the Lights vary considerably. In times of high solar activity (more on that later), the Lights may be seen in North America at latitudes as low as 35 degrees North, meaning that all but the southernmost parts of the United States may get a display. The offset of the Pole keeps solar storms from benefiting Europe quite as strongly, but most of the countries of northern Europe will get displays during periods of solar storms.
There is no guarantee of seeing the Northern Lights even if you are in the best areas at the best time, and there is some chance in others areas and seasons. However, a bit of planning will radically increase your chances. In short, pick somewhere on or very near the oval and go in the winter months.
Time of year 
Darkness is required. Most Northern Lights locations are found at high latitudes, meaning there is no darkness from mid-April until mid-August (even longer in far northern locations like Svalbard). In this period of time, no Northern Lights can be observed.
In the most intense Northern Lights areas, right on the oval, the lights are observed from late August to mid April. However, from late September to late March, it is dark after 6pm, and one enjoys maximum chances.
On a yearly basis, the Lights are at their peak in September and March. The reasons for this trend aren't fully known, but it's definitely real, not just an artifact of the weather or other viewing conditions.
Time of day 
The time between 6pm and 1am is the most intense period of the day. The highest probability within this timespan is between 10 and 11pm. However, this is a guideline, and during the Polar night aurorae can be observed as early as 4pm, and all through the night. In periods of strong activity, one can expect several flares starting at around 6pm, peaking around 10pm, and going on until 1pm.
11-year cycle 
In the longer term, auroral displays are correlated with an 11-year cycle in sunspot activity and other perturbations of the sun; the more restless the sun, the more aurorae. However, at the most favorable latitudes, the Lights are still likely to be seen even at solar minimum; it's mainly at lower latitudes that they get scarce during the inactive times. The next maximum in solar activity will be in about the autumn of 2013, with frequent Northern Lights displays likely for another two or three years after that.
Solar storms 
In addition to these more or less regular variations in frequency of the aurora, there are also less predictable, erratic displays resulting from solar storms. Some of these, particularly near solar-activity maximum, can lead to visible Northern Lights remarkably far South, if you're in an area with clear, transparent night skies. The largest recorded solar storm took place in 1859; the Lights were bright enough to read a newspaper in Boston and visible well South of there.
The "Alerts" section below will help you stay on top of solar activity and prepare for some viewing when a solar storm does occur.
Clear skies 
Last but not least, don't forget the weather forecast — aurora occur very high up in the atmosphere, and if there are clouds in the way you will not see anything. In Northern Scandinavia, the weather is notably better towards the end of the Northern Lights season (February-March), than in the beginning. The weather is probably the most important success factor in the areas under the Northern Lights oval, where there are visible Northern Lights on up to 80% of all clear nights.
If you have the luxury of being able to travel into aurora-viewing territory on short notice, you can improve your chances of seeing something by being aware of "space weather," the things going on beyond the earth's atmosphere as a result of solar activity. A good site for this information is operated by the (US) National Oceanic and Atmospheric Administration (NOAA), precisely for the purpose of keeping up on space weather. Measurements aboard the NOAA Polar-orbiting Operational Environmental Satellite are used for plotting maps of current extent and position of the auroral oval around both poles . Another useful tool is NOAA's test version of their OVATION model . It predicts intensity and geographical location of the auroral oval based on current solar wind conditions and interplanetary magnetic field virtually in real time. The maps show also observation limits of current aurorae. The commercial site Space Weather  presents much of the same information in digested, more accessible form.
The University of Alaska Fairbanks maintains an Aurora Alert website . For Finland, the Finnish Meteorological Institute has a activity forecast and current data about magnetic activity:  In Iceland the northern lights forecast can be seen here:  (provided by the Icelandic MET office)
Activity is mainly predicted from the readings taken by the NASA Advanced Composition Explorer (ACE) satellite, which gives an one-hour warning. Solar wind activity is characterized by three principal figures: the north-south component of the magnetic field (Bz), speed and density. When Bz is negative (southward), solar wind particles are best able to enter the atmosphere and give rise to aurorae. At high velocities, auroral activity may occur despite a moderately negative Bz. In geomagnetic storms, Bz fluctuates rapidly. Overall geomagnetic activity is characterized by the planetary K-index (Kp), for which predictions are issued. A Kp of 5 or higher occurs in storms and makes auroral viewing possible in the continental U.S. or in Finland, Sweden, Norway and northern Russia.
Longer-term estimates can be made by observation of the Sun for bursts. However, the physical models are poorly developed, partly because currently ACE is the only satellite in flight dedicated to solar wind, and the predictions are rather unreliable. The approximate day can be predicted, but whether the burst hits the Earth face-on and exactly when and at what force remains unknown. "Nowcasting" on the ground is done by measuring magnetic field fluctuations, and there are webcams pointed at the sky for directly seeing the aurorae. The NASA Polar and Environmental Satellites (POES) directly measure the extent of the auroral oval, but the satellites pass the pole about 14 times a day and thus the picture can be couple of hours old.
If a major solar storm develops that is forecast to have a good chance of producing Northern (and Southern) Lights, your time to respond will be measured in hours to a few days, rather than either minutes or weeks. The forecasts will usually include some indication of how far from the magnetic poles the activity is expected to extend. For purposes of travel planning, it's a good idea to plan conservatively and go to a locale somewhat closer to the pole than the maximum extent of the aurora; things don't always work out as forecast, and the Lights may be relatively weak and/or confined to the northern horizon if you're at the southern edge of the activity, either limitation possibly creating difficulties for you in viewing owing to light pollution.
Into the wild 
- See also: Travelling in cold weather
Because Aurorae are usually visible in the colder months of the year, the observers tend to spend long hours in cold darkness. Having in mind you will never feel too warm, it is essential to get dressed adequately to minimize the unpleasant side of the Auroral experience.
When getting clothes ready, don't forget about:
- Warm winter boots with thick soles: the cold comes from the feet first, mainly when standing on frozen ground / snow / ice.
- Warm (wool) cap covering ears or / and lined hood.
- Warm wind-stopper jacket.
- Hand warmers, mittens, or gloves: mittens have less surface area than gloves, so they lose less heat.
- For photography, you need to handle the camera and other equipment. It is common to wear a light pair of gloves for that with thick mittens over them to keep the hands warm the rest of the time.
- Long functional underwear.
- It is recommended to avoid cotton, because it keeps moisture which can contribute to hypothermia. Wool and synthetic fabrics are more suitable.
When selecting the observation site:
- If possible, park the car nearby to have the possibility of getting warm inside. A typical car heater cannot actually keep a large metal device warm when it is well below zero outside, but it is better than nothing and a car does provide shelter against wind. In really cold weather, leave the engine running even when you are away from the car since it may not restart if you shut it off.
- Avoid locations with light pollution; instead drive further away from populated areas. In more densely populated areas (usually in lower latitudes) it is good to have at least the northern view free of light pollution.
Consider bringing a tent or just a portable windbreak to provide some shelter from wind. Also vacuum flasks for hot beverages.
Taking good pictures of the Northern Lights is very difficult, since they're fast-moving, often faint and against a pitch-dark background, all of which befuddles consumer point-and-shoot cameras. Almost any interchangeable lens camera can handle the job, given the right lens, but the typical "kit lens" sold with them will almost certainly not be fast enough and may not be wide enough either.
Long exposures are often required to capture faint lights. Here's what you need for a sporting chance:
- A camera that supports manual exposure (5 to 40 seconds)
- A fast lens (aperture f/2.8 or better). Typically, a wide-angle lens is used to get a large area of sky.
- Fast film (800 ASA or better), or equivalent ISO setting on a digital camera
- A tripod to hold the long exposure
- Cable release or self-timer to trigger shots without stirring the camera
- Even better, for some cameras a remote control is available
- Manual focus. It is not recommended to just focus your lens to infinity, instead it is best done by aiming at the Moon or a bright star (ideally in the live-view mode and using the maximum zoom).
- Multiple spare batteries and memory cards: only that will insure they won't be needed. Keep the spares warm.
- What you don't need is the lens filter: it can cause interference, so better take it off your lens.
With a digital camera shooting in RAW format (or at least JPG + RAW) is a good idea: if something goes wrong in the field, there is more space for corrections in post-processing that way. Avoid breathing on the lens, the viewer or the display to prevent frosting them up. A light source such as a flashlight or headlamp can be useful when setting up the camera and tripod, and a smartphone is handy for alerts and forecasts. However, you need to get your eyes adjusted to darkness, so it is a good idea to limit use of these and set both phone and camera LCD displays to minimum brightness.
The ideal location has no light pollution, offers some shelter against wind, and is easily accessible. On a cold arctic night, you definitely want to avoid lugging camera and tripod a long distance or standing around in windy conditions waiting for the right shot. Also, try to get something interesting in the foreground; the photos in the first section of this article and the section just above are good examples. A shot of just the sky and some snow can be a bit boring even if the Lights are good. If possible, do some scouting by day so you can go straight to a good location at night. It is not always possible to find a great location, but even a reasonable one can give better photos with less discomfort.
Lens focal lengths
In discussing focal length, we assume a 35mm film camera or "full frame" digital camera. For other types of camera, the actual numbers are different but the "35mm equivalent" is often quoted, so this should work.
Either a zoom (variable focal length) or a prime (single focal length) lens can be used; each type has advantages. Zoom lenses are more flexible; you can adjust quickly for different sizes of light display. Primes are generally significantly faster than zooms, lighter and more compact; in many cases they also give a sharper picture than a zoom lens set to the same focal length.
Extreme wide angle lenses give some distortion, even producing "fish-eye" images at 10 mm or below. The photo to the right was taken with a 16mm lens; the horizon appears curved and the trees in the foreground appear slightly off vertical. Some viewers would not notice these distortion effects and few would find them bothersome, but with a still wider lens there might well be a problem. A slightly longer lens, perhaps 24mm, would reduce the distortion but cover less of the sky. This is where zoom lenses have a significant advantage over primes; with, say, a 16-35 zoom you can adjust each shot to get the best trade-off between distortion and coverage. In other conditions, you might carry several primes and adjust by swapping lenses, but this is remarkably inconvenient in the field in an arctic night.
Really fast lenses or high-ISO camera setting reduce exposure time, which is good. The photo to the right used an F2.8 lens and 25-second exposure. With F4, it would need 50 seconds, at or perhaps beyond the upper limit for practical shooting. An F1.4 lens would cut the time to around six seconds, quite likely giving a sharper photo because the lights would move less during exposure. A faster lens also allows a bit more control over the shot; if you hit the shutter release when the sky looks particularly interesting, it is more likely to stay that way for a few seconds than over a longer time. This is where prime lenses have an advantage; they are often quite a bit faster than zooms.
Combine a fast lens with a camera that allows high ISO settings and you might get exposure time down under a second, but it is not certain that this would give a better photo. High ISO settings give more noise in the image and you might lose more from that than you gain from the shorter time.
Fast wide lenses tend to be expensive. Checking full-frame Canon lenses on an American vendor's site mid-2013, the cheapest lenses that might be suitable for shooting the Lights are a 40mm F2.8 at about $150 or 35/2.0 at just under $300. Those are not wide enough to be ideal, but they would be usable and anything better is significantly more expensive. Typical choices would be 20 or 24mm F2.8 or the 17-40 F4 zoom, in the $500 to $750 price range. The ideal choice might be either a 24/1.4 prime or 16-35 F2.8 zoom, but these are high-end products mainly for professional photographers; either is around $1500. An ultra-wide 14mm F2.8 lens costs over $2000. Other brands have a different set of products and prices, but the overall pattern is similar. Lenses made by companies other than the camera manufacturer may come at lower prices or may offer options the camera maker does not provide, but again the pattern is similar.
Observing sites 
- See also: Winter in the Nordic countries
Northern Lights usually form about 100km (60 miles) above the surface of the earth. This means that an eruption is visible over large tracts of land. In principle, all areas under the Northern Lights oval are good observation points. However, most of these areas are remote and inaccessible, and suffer harsh climatic conditions.
Viewing or photographing the Lights is an activity where hiring a local guide or paying for a tour is often worthwhile. They are likely to know good sites and to have vehicles suitable for the conditions; a guide or tour may be no more costly than renting a vehicle and driving yourself. Some offer unusual transport options such as snowmobiles or sleds pulled by dogs, reindeer or horses, and most tourists could not safely drive those. Also, a guide's local knowledge can reduce risk and discomfort in several ways: coping with the weather, choosing good routes, and avoiding close encounters with dangerous wildlife such as polar bears or musk oxen.
Various locations provide some kind of infrastructure, like tours, observation points etc. Here is a list of some major ones:
North America 
- Fairbanks, Alaska: famous for aurora viewing, with many tours and sites that cater to aurora sighting.
- Yellowknife, in Canada's Northwest Territories, also with many tours
- Churchill, on Hudson's Bay in Manitoba, is right smack dab in the center of the auroral belt, and offers the opportunity to see (lots of) polar bears on the same trip.
North Atlantic Islands 
- Kangerlussuaq, Greenland: very high chance of seeing the Lights from November to March. If husky and snowmobile rides are desired, mid-late winter is recommended.
- Mývatn, Iceland: offers the unique experience of observing aurorae while soaking in a natural geothermal bath.
- Berneray, Outer Hebrides: this remote Scottish island offers suitable conditions for northern lights observation due to low light pollution.
- Tromsø, Northern Norway, is an easily accessible location with numerous excursions. Nearby Skibotn enjoys an extremely dry climate, thus providing excellent chances. Further to the northeast, Alta known for prehistoric rock carvings is sometimes called "the Aurora Borealis city".
- Jukkasjärvi, Northern Sweden, is the site of the original Ice Hotel, with excellent viewing infrastructure. Another 100 km northwest in Abisko, Norhern Lights can be watched from the Aurora Sky Station located at the top of the mountain Nuolja.
- Kilpisjärvi, Inari and Utsjoki in Finland have a 75% chance of aurorae per night. The skiing resort Saariselkä in Inari is a readily accessible target with unique accommodation in glass igloos specially designed for Northern Lights observers.
- The Kola Peninsula of Murmansk Oblast is Russia's most popular viewing spot.
The likelihood of seeing aurorae rapidly decreases when going South. In Helsinki, aurorae occur about once a month, and are usually masked by light pollution or clouds. Aurorae seen further outside of the auroral belts may also be much less vivid, with fewer colours.
A luxurious and usually expensive way to see the lights is to take a cruise ship along the coast of Norway or Alaska, or even toward Antarctica for the Southern Lights, in the appropriate season. There may be problems with this; not all cruise lines run in winter and it is extremely difficult to get good photos from a moving ship when the subject requires long exposures, as the lights generally do.
The Southern Lights 
Aurorae happen in a circle/ellipse about the South Magnetic Pole just as they do about the North one, and the South Magnetic Pole is similarly offset from the geographic South Pole.
Would-be observers of the Southern Lights or Aurora Australis benefit from the happy accident that the offset of the South Magnetic Pole is generally in the direction of Australia, although the Pole itself is still in Antarctica like the geographic one. Tasmania is therefore relatively favored for the Aurora Australis, and southern Australia and southern New Zealand get more than their share of Lights relative to latitude. Tasmania and New Zealand are still outside the auroral belt itself, though—if you want to get right under the lights, you'll have difficult travel ahead. The lights can be seen from the Antarctic Peninsula, but the optimal trip would be to Antarctica's Ross Sea via Macquarie Island (Australia) or the New Zealand Subantarctic Islands. The best viewing would be from the boat itself. The closest island to the auroral belt that has a good range of tourist accommodation is Stewart Island.
All of the considerations about maximizing your chances of seeing the Northern Lights apply equally to seeing the Southern Lights.