To answer this, we start with the sun whose energy production is far from even and fluctuates on an 11 year cycle. Maximum production coincides with high sunspot activity when processes on the sun’s surface throw particles far out in space. These particles are called the solar wind and cause the northern lights.
The sun’s surface temperature is approximately 6,000°C, much cooler than the interior which is several million degrees. In the sun’s atmosphere or corona, the temperature rises again to several million degrees. At such temperatures, collisions between gas particles can be so violent that atoms disintegrate into electrons and nuclei. What was once hydrogen becomes a gas of free electrons and protons called plasma. This plasma escapes from the sun’s corona through a hole in the sun’s magnetic field. As they escape, they are thrown out by the rotation of the sun in an ever widening spiral – the so-called garden-hose effect.
After 2-5 days’ travel trough space, the plasma reaches the earth’s magnetic field compressing it on the daylight side of the earth, and stretches it into a “tail” on the night side. A few of the particles penetrate down to the earth along the lines of magnetic field in the polar areas. Most, however, are forced around the earth by the magnetic field and enter the “tail” which stretches out into a long cylinder. Its diameter is equivalent to 30-60 times the earth’s radius, and its length up to 1000 times the same radius. It is, in effect, as if the earth’s magnetic field creates a tunnel in the plasma current from the solar wind. Inside one end is the earth, and around its surface the earth’s magnetism and the solar wind interact. The magnetic tail is divided into two by a sheet of plasma. The magnetic field lines from the earth’s north and south pole stretch out in their respective halves such that the fields are in opposition. The electrons and protons in each half of the plasma rotate in opposite direction forming a huge “dynamo” with the positive pole on the side of the plasma sheet facing dawn and the negative pole facing evening. The “dynamo” is driven by the current of charged particles between the two poles.
When the northern lights break out the following happens. The solar wind strengthens and the magnetic tail becomes unstable. Charged particles dive inwards towards the center of the tail and cause it to increase in length and to taper. The particles draw the magnetic field lines toward the center where they meet causing a magnetic “short-circuit” approximately 15 times the earth’s radius above the earth on the night side. This occurs especially at the “dynamo’s” two poles where a large amount of energy becomes stored. The magnetic field lines from both sides of the plasma layer now act as conductors in the “dynamo’s” outer circuit.
In northern regions like the Yukon, the best time to view the aurora is from late August to mid-April. During the summer months the night skies are not dark enough to see the aurora borealis even at times when the solar wind activity is strong. In midwinter the temperatures may fall to the minus 40 degree range and it is important to wear appropriate winter clothing (please see “winter clothing packages”) to enjoy the displays.
The most active region of the auroral oval typically becomes visible around local midnight. This region is also the widest part of the oval in the north-south direction, so your best chance of seeing aurora borealis is around local midnight. (Note that this is astronomical midnight, which may be an hour or two different from civil or “wall clock” midnight due to daylight savings time or other peculiarities in your time zone.)
Spectacular aurora borealis displays due to geomagnetic disturbances may be seen at any time when the sky is dark, but they are relatively unpredictable. Under average conditions, observations around local midnight are most likely to yield results.
It is not possible to predict auroral activity very far in advance. As solar activity increases and decreases in 11 year cycles, the forecast is less predictable, the further away from maximum activity we are. Forecasts usually are limited to a few days based on current observations of solar flares and sunspots.
So, if you are planning a trip month’s in advance, consider the previous questions above. Beyond that, we can truly say “your guess is as good as ours”.
However, you may want to consider the phases of the moon as the winter skies with snow on the ground may be very bright under a full moon. Therefore the darker nights around new moon seem to be better for the observation of the Aurora Borealis.
This question is always good for a lively discussion among residents of the north. So far, attempts to record sound during aurora have failed to produce any proof that such sounds exist, but it is hard to ignore the numerous reports that go back centuries.
There are generally two types of sounds reported to accompany the aurora borealis. The first is a swishing sound that changes with movements in that auroral display. The second type is a crackling sound, like static electricity makes.
The problem with claims of sound that changes in time with auroral movements is that the aurora is a long ways away (100 km/60 miles), so if sound was coming from the aurora borealis, there would be a long delay between the auroral movement and the sound arriving at the listener’s ears, just as thunder arrives long after a distant lightning flash is observed. There is also the small detail that the air between us and the aurora is far too thin to carry sound over such long distances. Therefore, if this kind of sound exists, it must be created very near to the observer.
The most likely explanation for this type of sound is that it is created inside the observer’s head: not a figment of the imagination, but rather leakage of the electrical impulses from the nerves in the eye (carrying images of the aurora to the brain) into the part of the brain the processes sound. In a very quiet environment, there are no sound signals for the brain to process, so it notices these tiny leakage signals and the result is sounds that change in time with the aurora. This explanation was actually tested by some early explorers, who found that the sound went away if their eyes were covered.
The second type of sound is more mysterious. A crackling sound, like static electricity sparking, might be explained by the strong electric and magnetic fields associated with the aurora, but so far theories and measurements have not provided a satisfactory explanation. Research continues.
Depending on the time of year you are chose to come for your visit to the Yukon the temperatures can be as cold as -40 degrees. In order to be safe and enjoy possible outdoor activities as well as looking at Aurora displays we strongly recommend the rental of the winter clothing package, unless you have good winter sport clothing at home that you are comfortable in.
There are many options to go out and eat in Whitehorse. The city offers a great variety of restaurants from fast food to high end establishments. Our guide will be happy to recommend places to eat, depending on your wishes.
The Aurora Borealis can be seen in Whitehorse, but the strong city lights are very distracting. That is the reason why we take our clients away from town to small cabins in the country side, where you will have an unobstructed and undisturbed view of the big northern skies.
