It's the return of the blog! Yippee! Starting strong with a subject that always raises many, many questions, the northern lights in southern Quebec! Recently, we had the immense privilege of observing a mind-blowing show in the night sky of Rimouski and elsewhere in the province. Magnificent aurora borealis lit up the sky for a few minutes during an evening when the forecast was very favourable. But what are these conditions, exactly?
First, for those who don't know, the aurora is a natural phenomenon caused by the interaction between particles from a solar flare, and different gases found in the atmosphere, such as nitrogen and oxygen. Ok, this can get a little technical, but we'll stick to the basics, I promise.
They are called polar auroras (borealis in the northern hemisphere or australis in the southern hemisphere) because these same particles are subject to the earth's magnetic field and are therefore attracted towards the poles when they arrive in the earth's atmosphere. In short, the turbulent surface of the sun ejects particles, the solar wind pushes them towards the Earth, they arrive by the poles and boom, light interaction. Careful here it is a very brief summary, but keep in mind that the more the solar wind is intense and hits with force, the more the oval that we see on the forecast maps extends, and the more we have chances of seeing them further south!
“Interestingly, most auroras are between 100 and 300 km above the ground!”
Mobile app AuroraNow gives you a map of the northern hemisphere and the aurora oval as well as the data explained in the glossary below (and more). Just like many other apps and websites, for that matter. If you see green light above your location on the map, get out there and try to see if you may spot them! The more colors above your geo location the map, the more chances you have!
You will find all the data on forecast websites or apps!
Kp : index measuring geomagnetic activity. Higher means more activity.
Bz (nT) : north-south component of the interplanetary magnetic field (in nanoTeslas). A negative Bz index indicates that the interplanetary magnetic field can "connect" with that of the earth (because their polarities are opposite), which will facilitate the penetration of particles into the earth's atmosphere. (e.g. -5 nT)
Bt (nT) : Total intensity of the interplanetary magnetic field (in nanoTeslas). (e.g. 10 nT)
Solar wind speed (km/s) : as mentioned above, faster, more impact, more chances.
From a photography point of view now, are the auroras as colorful and visible to the naked eye? Sometimes yes, sometimes no, but most of the time colors and brightness are enhanced by different settings of our camera. To successfully capture them, you will definitely need a tripod, a "fast" wide-angle lens if possible (e.g f1.4 or f2.8), a camera that tolerates high ISOs well and finally, a place with an unobstructed view to the north and away from any light pollution! Don't forget that clouds, precipitation and the full moon are not your best allies for a good observation! Feel free to leave me your comments/questions below and happy hunting!
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