Updated Recommendations for Travel to Alaska #10: Aurora Borealis

Aurora borealis in Denali National Park

In many of my posts in this series, I have talked about the aurora borealis, also known as the northern lights. This phenomenon is a primary reason we (and many other tourists) go to Alaska.

What is Aurora?

Aurora is caused by collisions among electrically charged gaseous particles from the Sun that enter Earth's atmosphere, blown here by solar winds. The charged particles are largely deflected by Earth's magnetic field, but, because Earth's magnetic field is weaker at the poles, some particles enter the atmosphere and collide with gas particles. These collisions emit light that we perceive as the dancing lights of the north (aurora borealis) and the south (aurora australis). 

Aurora borealis in Soldotna

The major cause of great aurora is a coronal mass ejection (CME), a large expulsion of plasma and magnetic field from the Sun's corona. 

A massive CME; Photo: NASA

CMEs can eject billions of tons of coronal material and carry an embedded magnetic field (frozen in flux) that is stronger than the background solar wind. CMEs travel outward from the Sun at speeds ranging from slower than 150 miles per second  to as fast as almost 1,900 miles per second. The fastest Earth-directed CMEs can reach our planet in as little as 15-18 hours. Slower CMEs can take several days to arrive. They expand in size as they travel; larger CMEs can reach a size comprising nearly a quarter of the space between Earth and the Sun.

Bright green above the Alaska pipeline

Auroral displays appear in many colors with pale green and pink the most common. 

Green is produced by oxygen molecules about 60 miles above the earth. 

Red/pink auroras are produced by oxygen at heights of up to 200 miles. 

Nitrogen produces blue or purplish-red aurora. 

The other colors usually mix with green

The lights of the aurora generally extend from 50 miles to as high as 400 miles above Earth. 

Aurora from space: Photo: NASA

The lights appear in many forms from patches or scattered clouds of light to streamers, arcs, rippling curtains or shooting rays that light up the sky with an eerie glow.

Interesting displays

Where, When and How Can You Find Aurora?

So, how do you know if there has been a CME and/or if aurora is expected? We depend heavily upon Spaceweather.com, a website that provides up-to-the-hour auroral maps and forecasts, plus posts a gallery of photos that make you wish you had been there.

A great tool

There are other aurora forecasting sites as well, but we're pretty devoted to Spaceweather.com.

To see aurora, you have to have a reasonably dark sky. Weak aurora can be seen only on a Moonless night far from any ambient light. Stronger aurora can be seen even when there is Moonlight, ambient light or even lingering sunset. But, it has to be dark enough for contrast.

The sun is still setting

This is the reason you can't chase aurora in mid-summer in Alaska. The southern parts have a few hours of night and even less of full dark. Above the Arctic Circle, there is no dark.

Fairbanks in February has plenty of dark

This doesn't mean you have to go in mid-winter (although you can). We've had fabulous aurora is spring and early fall. The advantage of spring and fall aurora is that you won't (probably) have to stand outside in -20°F temperatures, fumbling with your mittens to get a shot. The advantage of mid-winter is more hours of dark and, sometimes, crisper air. But, it can be cold.

It was very cold this night; Photo: Scott Stevens

But, dark alone won't do it. You also need clear skies, which means the foggy, rainy and misty parts of Alaska are tough for aurora viewing (that's why Iceland is also frustrating). Fairbanks and other places in the drier interior are the best.

You can see it with scattered clouds (you might get lucky and see a shooting star, too)

And, of course, you need actual auroral activity, So, cross your fingers and hope for major storms on the surface of the Sun. 

Some aurora is freakin' obvious, but it is often hard to tell if it is starting (and, therefore, if it is worth grabbing your gear and waiting for the show). We have learned that aurora shows up better in photos than it does to the naked eye – especially green aurora.

This would be hard to see with the naked eye

So, take a photograph. If you see green in the photo, get out there; something is happening.

Scott waiting to shoot

Photography

We expend a great deal of time, effort and money to find aurora so we can photograph it. And, we always want to try for better!

So, how do you get good photos? 

First, pick a good spot. We usually scout during the day so we don't miss amazing aurora by driving around looking for a good place to shoot.

You'll probably want a place away from city lights. But, maybe not!

Looking down on a city with lights above can be a good look if the sky is dark enough

In most cases, you'll need to shoot toward the north because that's the most common direction for good displays. They are the northern lights! But, the farther north you go, the less this holds true. I have experienced 360° aurora!

Nice foreground; Photo: Scott Stevens

If you can, find a nice foreground – mountains, trees or a lake. If the Moon is out, it can provide nice illumination on the foreground. If it isn't, you'll just get silhouettes. 

Don't stand too close to your foreground, however. You must have a good view of a wide expanse of sky.

And, make sure you pick a safe spot. It will be dark and the roads may have snow or ice, Don't get hit by a car!

We often find a pullout; Right Photo: Scott Stevens

You need a fast wide-angle lens. Mine is a 20mm F2.8. You must switch your lens to manual focus (it will not work if it tries to autofocus) and then pre-focus it on almost infinity and tape it in place with gaffer's tape so you won't accidentally move it and lose focus.

Then, set the camera on manual and set it up on a tripod. I like to use a remote switch to minimize shake; it's a long exposure and any vibration will blur the photo. This is why aurora is very tough to shoot on a boat or from a moving vehicle.

Land-based is better

ISO and shutter speed depend on how bright the lights are and how dark the sky is. I shoot most of mine at 8-15 seconds on ISO 400-500. And, take advantage of the "fast" aperture (fast lens let in more light at lower shutter speeds). On a 2.8 lens, set it at 2.8. A slower lens might not get you the results you want.

15 seconds, f2.8, ISO 500

Don't touch your aperture after that, but do play with shutter speed and aperture. Shutter speed higher than 30 seconds will blur stars, so just stay in the 5-30 second range. ISO can go very high, but the higher you go, the grainier your shot will be. I don't like to go over 6400.

Much brighter than the actual shot

Because you are shooting in the dark, you need to turn the illumination on your camera's view screen down or else the screen will blind you (and annoy any other photographers in the area). Plus, because of the contrast with the dark, a shot that looks good on your camera screen is probably underexposed. 

You can adjust to get a natural sky

You want it to look too bright, but with definition. 

Bump up the ISO or increase the exposure until it looks right. If it is too bright (blown out), adjust down.

Later, you can fix issues – exposure, color, clarity, grain – with Photo, Lightroom, Photoshop or Topaz AI. 

 My camera, a Canon, tends to shoot on the red side, so I adjust my photos to make the sky as blue as it really was. Nikons shoot cooler.

This has a redder cast

Make sure you have ample batteries (especially if it is cold) and cards with you. You want to be able to take way more photos than you'll need to get the best exposures. And, cold kills batteries.

If there are other photographers around, minimize any lights (camera screens, flashlights, headlamps, care lights) as much as you can.

Some headlights lit up the foreground (that isn't always bad)

Having said all that, I have seen some pretty good shots taken with cellphones. I believe there are even special programs to shoot aurora on cell cameras.

Enjoy

The last tip is the most important: don't let trying to get the perfect photo distract you from actually seeing the aurora. 

It is magnificent to behold!