How to Photograph the Northern Lights

What Are the Northern Lights?

There’s never a dull moment when it comes to the Sun, our local star. Every minute of every day, it emits electrically charged particles, called ions, that travel across 93 million miles of space before impacting the Earth’s magnetosphere. When they do, the Earth’s magnetic field safely deflects those ions toward the poles, charging oxygen and hydrogen molecules in the Earth’s atmosphere along the way. This causes those molecules to glow, and as a result, we see aurorae.

Since the ions are deflected toward both poles, it’s possible to see the aurorae close to both the northern and the southern poles. In the northern hemisphere, the phenomenon is known as the aurora borealis, or northern lights, whereas in the southern hemisphere, it is known as the aurora australis, or southern lights.

What Causes the Colors in the Northern Lights?

We’ve all seen the stunning images of the northern lights online and in books and magazines, and we’ve all seen the video footage in documentaries - but what causes those colors? As mentioned earlier, the ions charge oxygen and hydrogen molecules in the Earth’s atmosphere, and the colors you see will depend upon the type of molecule being charged and the altitude of the molecules in question.

But before we talk about the colors, let’s put things into perspective. On average, a commercial airliner will fly at around 37,000 feet, which is equivalent to about 7 miles (11 km), while meteors will burn up in the atmosphere at an altitude of around 40 miles (60 km).

Blue and purple aurorae are caused by ions charging diatomic nitrogen and occur at the lowest altitude - sometimes as low as 50 miles (80 km), but more usually between 60 miles (100km) and 190 miles (300 km.)

Green aurorae occur at a similar, if slightly higher, altitude and occur when ions interact with monatomic oxygen molecules between 60 and 190 miles (100km to 300km). Our eyes are particularly sensitive to green light, and so we tend to see more green aurorae than any other.

Red aurorae usually occur at the highest altitude, somewhere between 190 miles (300 km) and 250 miles (400 km.) These are also caused by monatomic oxygen molecules. (Incidentally, red aurorae are the type of aurorae most commonly seen at lower latitudes, as the curvature of the Earth will hide the lower altitude aurorae from view.)

Finally, yellow and pink aurorae, while rare, can be seen when a coronal mass ejection (CME, see below) hits the Earth’s magnetosphere. When this happens, the blue aurorae mix with green to produce yellow, while pink aurorae can be seen when the blue aurorae mix with the lower-altitude red aurorae.

Where and When Can You See the Northern Lights?

Thanks to the shape of the Earth’s magnetosphere, the northern lights are most commonly seen at latitudes of between 60 and 75 degrees north. (Conversely, the southern lights are most commonly seen between 60 and 75 degrees south, where there is no human population to speak of.) This being the case, some of the best places to see the northern lights on any clear night are:

Since these locations are in the far northern hemisphere, you’ll want to avoid visiting during the spring, when the nights are growing shorter, or the summer, when the sky is never truly dark. And, of course, some locations will be within the Arctic Circle, which means the Sun might not set at all during part of the summer.

Late autumn and, especially, winter are ideal, as the nights will be long and dark, giving you the best chance of seeing the northern lights for yourself. The downside? It can be bitterly cold, so be sure to wrap up warm!

Coronal Mass Ejections (CMEs) and the Northern Lights

As many people know, there are times when the Sun plays a much larger role in the appearance of the northern lights. During periods of increased solar activity, the Sun can produce coronal mass ejections or CMEs. A CME occurs when the Sun ejects a huge cloud of plasma from its corona into space, which can then hit the Earth anywhere between 15 hours and a few days later. When it does, the magnetosphere receives an enormous shock - literally.

When the impact occurs, the Earth’s magnetosphere becomes distorted and compressed, exposing satellites to harmful radiation. Similarly, the area on and around the Earth can become charged, leading to problems with the electrical grid, satellite and radio communications and, of course, stronger aurorae.

Since a CME produces a far greater number of charged particles, they are spread further afield than usual by the magnetic field. As a result, aurorae can be seen at lower latitudes, such as the entirety of Canada, mid-latitude, northern United States, the United Kingdom, and the northern half of Europe. Under extreme circumstances (such as the Carrington Event of 1889), aurorae have even been seen in the tropics.

What Do the Northern Lights Look Like to the Naked Eye?

Unless you live at a latitude where you can regularly see the northern lights, you’ll want to know if and when they might be visible from your location. It’s, therefore, a good idea to download an aurora app or keep your eye on the news for any potential activity. For example, one excellent resource is SpaceWeather.com, which provides current data on the Sun and includes a graphic depicting where in the world you can expect to see aurorae at the current time. The site also provides a daily email newsletter, so you’ll never need to worry about missing a potential sighting again.

So you’ve had a notification that the aurorae might be visible from your area tonight. What's next? First, check the phase of the Moon. Unless the northern lights are expected to put on a strong show, you may find the moonlight brightening the sky and overpowering the light from the aurorae. Generally speaking, if the Moon is above the horizon and between first and last quarter (especially around full Moon) it could cause a problem.

Next, make sure you know which way is north. You only need to know the approximate direction, so if you’re not familiar with finding Polaris, the Pole Star, you can step outside during the day and look for the Sun. It’s best to go outside around midday when the Sun is toward the south and then turn and look in the opposite direction. (Alternatively, go outside at sunset, face the Sun, and then make a quarter turn to your right.) Make a mental note of any landmarks you see, as this will help you find north after dark.

Finally, wait for the sky to become truly dark at the end of astronomical twilight. A number of astronomy apps can give you this information, but otherwise, you can go to timeanddate.com, enter your location and the site will tell you when night begins and ends. (Incidentally, it’s not a bad idea to let your eyes adjust to the dark, too, but if the northern lights are sufficiently bright, dark-adapting your eyes shouldn’t play a major role in your ability to see them.)

So now you’re standing outside in the dark, facing north - what can you expect to see? To some extent, this will depend on how far south you are and the strength of the storm. Most of the time, from mid-latitudes, the northern lights can appear faint and almost smoke-like in appearance. You might even mistake the aurora for a cloud, but there are a couple of things that set it apart. For starters, you’ll notice that it has a subtle color (often red, from mid-northern latitudes.) Then you’ll notice it slowly moving from north to south but changing shape as it drifts across the sky. Little wonder, then, that our ancestors often thought they were the spirits of the deceased!

How to Photograph the Northern Lights

Once you’ve seen them for yourself, you’ll no doubt want to capture the moment for posterity. The good news is that you don’t need any expensive photographic equipment to do this, as even a cell phone can potentially do the job.

However, before we get into the details, you should know that it’s worth investing in a tripod, as this will keep the camera steady and ensure your images are crystal clear. You don’t need to spend a lot of money either, with the Celestron Ultima Pan Tilt Head Tripod being an excellent choice. (Cell phone users will also need to buy an adapter, but these are very inexpensive.)

Another good idea is a remote shutter, as touching the button on your camera or cell phone will cause it to shake. You can potentially get around this by setting a shutter delay (typically 10, 20, or 30 seconds), but by that time, your view of the aurorae may have changed. These are also relatively inexpensive and can save you a lot of frustration by helping you avoid the blurry images that might otherwise result.

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Photographing aurorae with a cell phone

Nowadays, pretty much everyone has a cell phone with a camera, and with today’s technology, these cameras can capture some great images of the night sky. First, be sure to hold your phone horizontally so it captures the image in landscape mode. This will allow your phone to capture more of the sky (and any scenery that might also be present) and make for a better photo. You’ll also need to put your cell phone’s camera into manual mode (or Pro mode, depending on your phone). You could use Night Mode, but you’ll probably get better results if you change the settings yourself and experiment a little.

Next, you’ll need to set your ISO. The darker your surroundings, the higher the ISO will need to be, but as a general rule, 800 is a good starting point. As with everything else, this is really a case of trial and error and may need to be adjusted as you review the images. For example, you may find that a higher ISO works well, but be aware that this might also result in a grainier image.

Unless the aurorae are particularly bright, you’ll want to set the exposure time fairly high. This will allow the camera to absorb as much light as possible, resulting in a brighter, more colorful image. A 30-second exposure, if available, is a good starting point here, but if your phone doesn’t allow the shutter to stay open that long, go for the longest setting available.

In many cases, these two settings will be enough to capture some admirable images, but if not, you might also need to adjust the focus and the exposure. For example, if you have foreground objects (such as buildings) or scenery (such as hills or mountains), then manually adjusting the focus will ensure these remain sharp.

If the aurorae appear too bright and over-exposed in your photos or barely show up at all, then you’ll need to adjust the exposure setting on your phone. By default, this will be set to zero, with many phones having a range of between -1 and +1. If your aurorae are too bright, you’ll need to lower the exposure closer to -1, whereas if they appear too faint, you’ll need to increase it to closer to +1.

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Photographing aurorae with a DSLR camera

It’s a similar story if you’re using a DSLR camera. Again, you’ll want to make sure your camera is set to manual mode so you can adjust the settings for the best results. First, set the aperture to the widest possible, which ideally will be f/2.8 or lower. Also, as with cell phones, the ISO and exposure time will also need to be adjusted. Again, a good starting point for the ISO is 800, but you could go as high as your camera’s maximum setting. Conversely, if the moon is bright, nearby streetlights are on, or the aurorae are relatively slow-moving, setting the ISO at the lower end of the scale may yield better results.

In terms of exposure time, somewhere between 1 and 15 seconds is often enough, but it will depend on the speed and strength of the aurorae. The faster and stronger the aurorae, the lower the shutter speed. Again, this is trial and error.

Another setting you’ll need to adjust is the white balance to allow the aurorae to be seen in their true colors. If there’s moonlight, a lower value of between 3500K and 4000K should do the trick, while on moonless nights it can be set as high as 5500K.

Finally, we come to focus. Opinions differ on this, but the easiest option is to set your focus to infinity, which will allow the camera to focus on the sky. Alternatively, you can try setting the camera to manual focus and then choosing a bright star to focus on. If you choose to focus this way, be sure to take some test shots and then check the images on your camera’s LCD screen. Zoom in to ensure the star appears pinpoint sharp, and adjust the focus as necessary.