What causes the northern lights

What Causes the Northern Lights?

The northern lights (aurora borealis), are caused by the sun’s particles hitting the upper magnetic field of the earth’s atmosphere at an incredibly high rate of speed.

Since these particles are charged, they align themselves with the earth’s magnetic field lines and tend to form a ring within the gases where these field lines converge.

Here are some interesting facts about what causes the northern lights:

  • The northern lights start at approximately 60 miles and extend to 600 miles above the surface of the earth and can be seen from outer space.
  • The air at these altitudes is made up mostly of nitrogen and oxygen atoms.
  • When the sun’s charged particles hit these nitrogen and oxygen atoms they gain energy.
  • When the atoms eventually relax they give up this energy in the form of photons of light.
  • Oxygen atoms emit green light while nitrogen atoms emit light that is more orange or red.

Now it is true the northern lights are the most popular and vivid in photographs when searched around the web, however, the southern pole also experiences the aurora phenomenon as well.

In fact, all planets will exhibit aurora at its’ north and south poles. One of the world’s most popular destinations for observing the northern lights is in a small town in northern Canada called Yellowknife.

A short drive outside of Yellowknife and you are venturing into some of the darkest skies on the planet which makes it an ideal destination for viewing the northern lights. It lies approximately 250 miles south of the Arctic Circle and has a population of roughly 20,000 people.

Because of this, people from all over the world will travel here year to catch a glimpse of the northern lights in all its glory.

What can you expect to see in the northern lights?

The northern lights, or aurora oval is a gigantic ring that encircles the north-most region of the planet. It represents the convergence of the earth’s magnetic field lines where the sun’s charged particles collide with the earth’s nitrogen and oxygen atoms abundant in the upper atmosphere.

what causes the northern lights
Image source: NASA

While, theoretically speaking at least, the northern lights can exhibit any color in the spectrum, the most prominent we see here on earth is the green hue caused by the photons being emitted from the oxygen atoms.

Typically this green coloring will be accompanied by various shades of violet, yellow, blue, orange, pink and red lined throughout. This is what makes the northern lights a truly spectacular sight to behold in the night sky.

How to photograph the northern lights?

Without question, if you’re travelling to Yellowknife in the Northwest Territories of Canada to view the northern lights, you better make sure you come prepared to take some awesome photographs.

Taking pictures of astronomical type phenomena is much different than taking a picture of your son’s soccer game.

For one, you’ll be shooting a night with very little light to aid you, this alone can be quite a challenge to say the least and you need to understand things like exposure times and ISO settings.

Before I get into camera settings and gear, what you’ll want to do is find your perfect backdrop for capturing the northern lights. Remember the darker the sky, the more the northern light will “pop” against the infinite darkness that is the night sky.

Consider a location that is fairly flat with possibly some terrain and a lakes in the distance for effect.

Image source: NASA

Another consideration you must contemplate is the time of year you’re looking to travel to view and photograph the northern lights. Typically you’ll want to avoid April though August as the sky never truly reaches its pinnacle of darkness.

It is recommended for northern light viewing and photographing that you try to align with one of either the vernal equinox (March) or the autumnal equinox (September). During these periods the sun is exactly above the equator making the skies in the northern-most regions of the planet their darkest.

Gear Needed to Photograph the Northern Lights

You’ll want to make sure you have all the gear you’ll need to photograph the northern lights…especially if traveling to Yellowknife. I’m not sure if things have changed, but at the time of this writing Amazon Prime wasn’t shipping to Yellowknife in two days or less!

Sturdy tripod – without question you’ll want to have a good quality tripod for all your astronomical photography adventures. There are lots to choose from, but my general rule is this: you get what you pay for when it comes to tripods. I recommend Manfrotto tripods readily available on Amazon.

Full frame camera – you’ll want to invest in a full frame camera capable of shooting in low light conditions. I recommend the Nikon D810 if you’re budget allows, or if you’re on a bit of a tighter budget the Nikon D750.

Fast wide-angle lenses – I recommend purchasing fast wide-angle lenses for shooting astronomical events. Lenses with smaller “f-stops” numbers indicate the speed of the lens and you’ll want ensure a minimum of f/2.8. As far as focal length goes, I recommend lenses with a 14mm, 24mm or 50mm range. If you’re just getting into photographing the heavens, I recommend starting with a “nifty fifty”.

Steps to Photographing the Northern Lights

Step 1: Set your Camera to Manual

  • Set your camera to Manual mode
  • Turn auto-focus off on your lens
  • Turn off image stabilization on your lens
  • Turn your flash off

You will need to set your camera in Manual mode in order to have control over your exposure time. When shooting in dark conditions, you’re camera will not be able to automatically configure the exposure time, therefore, manual action is needed.

If you leave your auto-focus on, your camera will continuously “hunt” for optimal focus conditions. Of course, because it is dark, you’re camera will likely never find them, so a manual focus is optimal.

Also remember to turn off your flash. Leaving auto-flash enabled will diminish your image and render it completely useless – and at this same blind everyone you’re with! Flash will emit harmful light pollutants into your surroundings so turn it to OFF.

Step 2: Adjust your ISO settings

  • Start with an ISO setting of 1600

Generally, when shooting astronomical images you’ll need to increase your ISO settings. A setting of 1600 is usually a good starting point for shooting at night.

The less light you have to work with, the more ISO you are going to need to add to be able to “develop” an image.

A word of caution though, you should always try to use ISO sparingly because it will lessen the image quality the more you add – making your image “noisier”.

If you have a relatively newer, good quality camera such as the Nikon D810 or Nikon D750 recommended above, using an ISO of 1600 or higher will not be an issue. This is where you really start to see the cheaper cameras for under $1000 start to fall off as you move up in ISO.

Step 3: Use a Wide-angle Lens

  • Use a wide-angled lens with a focal length between 14mm and 50mm
  • Ensure the lens speed is f/2.8 or lower

As mentioned above, you’ll want to use a wide-angle lens in order to capture the Northern Lights against your chosen backdrop.

I recommend bringing with you an assortment of high quality 14mm, 24mm, and 50mm wide-angle lenses with the lowest f-stop number possible but no higher than f/2.8.

This is true not only if you’re shooting the northern lights, but any astronomical images as well.

The f-stop number is critical because it indicates the amount of light the lens can gather at a given instant. The more light your lens can take in, the lower the shutter speed you can use. All crucial when shooting under dark skies.

Step 4: Adjust the Shutter Speed

  • Start with a shutter speed of 20 seconds

Shutter speed is the amount of exposure time you give to your image. This is another important setting that you don’t have the luxury of leaving in automatic mode when shooting at night.

I recommend setting the shutter speed to 20 seconds as a starting point. Depending how intense the light source is your shooting, in this case the northern lights, you may need to increase the exposure time, or decrease the exposure time.

One caveat with increasing it is if you go too long you risk seeing star trails in your images…which can be cool too depending on the effect you’re going for!

Step 5: Mount your Camera on a Tripod

  • Mount your camera on a tripod

Mounting your camera on a tripod is of paramount importance. As I said previously in this article, “don’t skimp out on the tripod”.

You’ll want to ensure that you purchase a good quality mount when shooting outside and especially at night.

Any kind of camera shake will have drastic effects on your image quality. As I recommended above, Manfrotto tripods are well built, and well priced to do the job!

Step 6: Set your Focus

  • Set you lens to the infinity symbol if it has one
  • When possible setup your focus during the day
  • Use a distant object to set your focus, such as the moon or a bright star

As mentioned in Step 1, auto-focus simply will not work at night. Your camera will continuously hunt for an ideal focus if left enabled and it will never find it. This is perhaps the trickiest part of the entire setup when shooting at night.

When at all possible try to setup your focus just before dark by bring into focus a distant object such as a distance tree-top, the moon or a star. It is imperative that you get comfortable with the manual focus adjustment on your camera lens before venturing out at night.

That said, it is important to get comfortable with all the settings mentioned thus far before venturing out in the cold at night because it will be that much more difficult when you cannot see!

Step 7: Remotely Control the Shutter

  • Use a remote shutter device
  • If the camera connects wirelessly to your phone, use an app

This is another important piece of equipment that should be in your camera bag – a Remote Camera Shutter. This again lessens the impact of camera shake by allowing you to remotely close the shutter without physically touching the camera.

Many newer cameras now will allow you to connect you cell phone either Bluetooth or wireless to provide remote shutter functionality as well as configure many of the settings we’ve discussed remotely.

Final Words…

Well there you have it, hopefully a detailed answer to “What Causes the Northern Lights” as well as some useful tips, tricks and places to photograph the northern lights in all their glory. I certainly hope you’ve enjoyed reading this article and have found it both interesting and useful.

Please check out some of my other equally interesting articles: