Aurora Mythbusing

12 months ago 43

There are a lot of misconceptions and misinformation out there about the aurora borealis. We have found that this can sometimes set up expectations that can get in the way of enjoying the aurora chasing experience. (This list is...

There are a lot of misconceptions and misinformation out there about the aurora borealis. We have found that this can sometimes set up expectations that can get in the way of enjoying the aurora chasing experience. (This list is not in any particular order – it was hard to prioritize.)

Myth No. 1 – “The aurora only comes out in the cold.”

Aurora borealis and frosty trees near Girdwood.

This is one of those times when you need to know the difference between correlation and causation. Cold temperatures do not cause the aurora borealis. It’s really cold in space or at distances of 200 miles in altitude, much colder than down here on Earth, so temperature has nothing to do with it. However, in the winter months when the skies are clear, that always results in colder temperatures. And clear skies often provide good aurora viewing (but not required, as noted below). When the skies get dark enough in early August near Anchorage, temperatures can still be warm enough sometimes to photograph in a short-sleeve shirt.

Myth No. 2 – “The best time to see the northern lights is in the middle of winter.”

Aurora borealis and Christmas tree in yard on Anchorage hillside

We actually had someone criticize us recently on a TripAdvisor review for running tours in the autumn when we should only be running our northern lights tour in the middle of winter. His rationale was that the aurora is only visible in the middle of winter. Everyone knows that, right? Perhaps the assumption is that it is only visible during the darker days (or, as noted above, when it is cold).

We have known for a long time that there is a semiannual variation of the magnetic field that centers around the equinoxes. One of the things that can most influence the appearance and activity of the aurora borealis is when cracks form in our magnetic field, allowing the charged particles from the sun to penetrate and interact with oxygen and nitrogen in the atmosphere. These cracks occur more frequently at around the fall and spring equinoxes. A study of 75 years of aurora activity published in 2007 by NASA scientist David Hathaway provides some solid data for knowing which months specifically are the best.

When reviewing the monthly averages of the average number of days with a geomagnetic storm and the average daily Planetary K-Index (Kp value), the months around the fall and spring equinox months clearly stand out.

Myth No. 3 – “This will be the last chance to see the northern lights before they dim for a decade.”

This is a common click-bait tactic by supposed travel news websites seeking to attract attention. It is based on the roughly eleven-year cycle that the sun goes through, ranging between Solar Minimum to Solar Maximum and back to Solar Minimum again. The claim is that when we leave Solar Maximum, you can no longer see the northern lights.

Whether the sun is at maximum or minimum is partially calculated by the frequency of sunspots. A Solar Minimum may see a period of over 200 days without any sunspots appearing, but a Solar Maximum may see several new ones in a day. When there are long periods without any sunspot activity, it takes a while for scientists to determine which is the longest period without sunspots, and thus when Solar Minimum occurs.

While Solar Maximum may be indicated by peak sunspot activity, another things occurs that signifies Solar Maximum – the sun’s polarity reverses. Once this occurs, we know that Solar Maximum has concluded and we have started the downward slide to Solar Minimum.

But the aurora borealis does not “disappear” during Solar Minimum. It just occurs less frequently or only at higher latitudes. During a ten-day float of the Noatak River in Alaska in September 2008, during a Solar Minimum, I had the pleasure of seeing the northern lights every night we had clear skies. So if you are traveling to see the northern lights during a Solar Minimum, just go farther north and around the equinoxes to increase your chances.

As of now, it is projected that the next Solar Maximum will occur in early 2024.

Myth No. 4 – “You cannot see the northern lights under a full moon.”

Aurora borealis over Susitna River, Alaska, under a 99% illuminated moon.

It is commonly asserted that you should only go aurora chasing under a new moon, that a moon will make it impossible to see the northern lights. It is true that a bright moon will make it more difficult to see the northern lights, but not impossible. Our data indicates that once the moon reaches 40% illumination, it starts to make viewing a quiet aurora challenging, but not impossible. “Quiet” aurora level is Kp0-2. Once moon illumination reaches around 70%, then viewing a quiet aurora becomes impossible. You can see the aurora, but it needs to be a Kp3 and have a hemispheric power of at least 45.

So, to see a quiet aurora, and maybe some Milky Way, it is a better time to try seeing the northern lights when the moon is 40% illumination or less. But it’s not the only time you can see them.

Myth No. 5 – “You need a clear, dark night to see the northern lights.”

Having a clear night, and a dark night, does increase your chances of seeing the northern lights. But those are not the only conditions when you can see them.

It is possible to see the northern lights with some cloud cover. High altitude clouds are often thin enough to view bright aurora displays through them. And even on cloudier nights, a bright aurora can be seen behind the clouds or in gaps in the clouds.

The night does not have to be perfectly dark, either. Like the earlier discussion with the brightness of the moon, the appearance of twilight is also a factor in viewing the aurora borealis. Generally speaking, you want to have at least the darkness of astronomical twilight in order to see the northern lights. But with a more active, brighter aurora display like a geomagnetic storm, you can see the northern lights in a brighter twilight like nautical twilight or even civil twilight.

Aurora borealis in twilight over trees and cabin, Fort Yukon, Alaska, in nautical twilight.

Myth No. 6 – “You have to go to Fairbanks to see the northern lights in Alaska.”

When I give presentations and talk about salmon, I ask the audience how many people have heard of Copper River Sockeye salmon. Most of the hands in the audience go up. But when I ask how many have heard of Bristol Bay Sockeye salmon, few hands go up. This despite the fact that the odds are good that most of them have eaten Bristol Bay Sockeye salmon because that region of Alaska supplies 50% of the world’s Sockeye Salmon supply. The reason they have heard of Copper River salmon is marketing.

That, quite frankly, is why so many people – even hotel staff in Anchorage – think that you have to go to Fairbanks to see the northern lights in Alaska. Marketing. While it is statistically accurate that you do have a higher chance on average of seeing the northern lights in Fairbanks – it is farther north and has a slightly higher average of clear nights in the winter – that does not mean that Fairbanks is the only place you can see it. In fact, we have had many guests on our Anchorage Aurora Quest tour tell us they have not seen the northern lights during trips to Finland, Iceland, and Fairbanks … but finally got to see them on our tour.

Here is a simple graphic illustrating the differences between the northern lights viewing experience in Fairbanks and Anchorage:

For those who may concede that you can see the northern lights in Anchorage, they will still stay, “You have to get out of the city because of the bright lights.” The same is true with Fairbanks. On a normal activity night, the lights of Fairbanks are too bright to enjoy the aurora. And because Fairbanks and its surrounding communities are not geographically constrained like Anchorage, you have to get quite a ways away from Fairbanks to get away from the light pollution. On an active aurora night, the northern lights can be seen directly over the city of Anchorage.

Northern lights over downtown Anchorage during a G1 geomagnetic storm

Myth No. 7 : “You cannot hear the aurora borealis.”

Much like the American Medical Association for a long term referred to chiropractic care as voodoo or witch doctor medicine, scientists have long dismissed the notion that you can hear the northern lights. They had long dismissed as folklore any reported sounds of crackling or whooshing noises caused by the northern lights.

Finnish Emeritus Professor and speech technology expert Unto Laine started actively studying the reported sounds of the aurora borealis in 2000. Laine presented his findings in a paper published in 2016, focusing on the crackling and popping sounds during an aurora. Most of the time the auroras were silent, but to their surprise they found that about 5% of the strongest auroras were associated with whistles, cracks and hisses. The studies found that the noises always coincided with a temperature inversion (cold air trapped under a lid of warm air) and appear to be caused by the release of static charge, linked to changes in atmospheric electricity caused by the aurora’s disturbance to Earth’s magnetic field. After Laine set up recording equipment in the Finnish village of Fiskars in 2022, he even discovered that the sounds can sometimes occur without any northern lights present.

I have heard the crackling sounds of the aurora borealis once, while photographing a G3 geomagnetic storm in Portage Valley, Chugach National Forest, Alaska, on March 17, 2013.

Myth No. 8: “This is what the aurora borealis always looks like”

A corona display from a Kp6 aurora soars over Mt. Sukakpak, Brooks Range, Alaska.

I have heard the following phrase more than once, and even on nights with really good displays: “That didn’t meet my expectations.” This indicates that photos on social media have definitely misled people to think that the aurora is always spectacular. There are three layers to peel back on the notion that every aurora should look like the one displayed immediately above.

First things first, most of the colors in the photo above were not visible to the naked eye when this photo was taken. The aurora looked bright green, surrounded by light grey tones. (Those grey tones ended up being the purple and red in the photo.) That is because most of the colors in the aurora cannot be perceived by our eyes. The cones in our eyes that transmit color data to our brain do not work in darker conditions. The ability of the camera to take longer exposures is what allows colors like red, pink or purple show in in the camera, but not as we are looking at them. (See our earlier blog post about understanding the colors of the aurora.)

Second, the photo above was taken during a G2 geomagnetic storm. Geomagnetic storms are not particularly common. As noted above, even the peak month of March experiences only 9.55 geomagnetic storms on average. The key word is average. For example, while October experiences 8.4 geomagnetic storms on average, there were only three in the entire month of October 2023 for our viewing hours in Alaska.

Lastly, the type of aurora shown in the photo immediately above is called a “corona.” These are even more rare than geomagnetic storms.

Simply put, if the photo above is what you expect the aurora always looks like, you are setting yourself up for disappointment.

The following images are more of what the aurora typically looks like, which is on nights when there is not a geomagnetic storm (which is most of the time):

Myth No. 9: “A high Kp means great aurora.”

This is perhaps one of the greatest misconceptions about the northern lights. It is unfortunately routinely perpetrated by broadcast and print media that does not understand the science of the northern lights.

The Planetary K-Index, or Kp for short, is a globally-averaged indicator of the level of geomagnetic activity. It is measured on a scale from 0-9 and indicates how far south the aurora might be visible. The main driving factor in visibility and activity of the aurora is actually the Interplanetary Magnetic Field (IMF). The IMF is the magnetic charge of the sun, flung out into space on the solar winds. It is measured in units of Btotal (strength) and Bz (polarity). For good displays, we want the Bz to be negative, or south. The greater the number, the better. This is because the Earth’s magnetic field is always positive, or north. Just think of how two magnets attract – one has to be negative, the other positive. To illustrate, I have been out during a Kp7 (G3 storm) aurora, but seen absolutely nothing because the Bz was +25 north. But I have seen good displays at Kp0 when the Bz dropped suddenly to -10 south.

Unfortunately, what the IMF will do on any given night is not something that can be forecasted. And quite frequently, the Bz will pop back and forth between south and north throughout the night. (Check out the NOAA Space Weather Prediction Center’s Real Time Solar Wind page, looking at the top graph.) You can see the short term Bz forecast while out chasing the aurora, because satellites detect the polarity of the incoming solar winds. That data can be tracked on a variety of apps. We recommend Amazing Aurora for tracking short-term forecasts of up to one hour.

Myth No. 10: “Tour operators can control the weather and the aurora borealis.”

I know what you are thinking, “That’s nuts!” And yet, people still issue 1-star reviews for cancelling a tour due to bad weather or not seeing the aurora borealis. This is a problem related to Myth No. 8, in that people simply lack and understanding about the aurora borealis.

Let us make the record clear: tour operators cannot control the weather. And no, we cannot use HAARP to create the northern lights.


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