Long before science could explain what they were, the wonder and fear that the Northern lights inspire have been captured around the world in myths and stories. Of these, my favourite hails from Finland, where legend has it that sparks are created through the night sky by foxes as they run across the frozen tundra. Hence, the finnish call the Northern lights Revontulet, or “Fox Fires”.
Science tells us that the Aurora Borealis is a show of excited electrons from the solar wind interacting with the earth’s atmosphere. Solar winds stream away from the sun at 1.5 km/h, reaching the earth’s atmosphere around 40 hours later. The winds follow the magnetic field around the earth, so the light show is most often seen around the magnetic north and south poles, around the Arctic and Antarctic circles, respectively. The colours depend on the component that the charged electrons interact with and the altitude:
- Green (most common)- oxygen, 100-300 km up
- Pink – nitrogen, around 100 km up
- Red – oxygen, above 300 km
- Blue/violet – nitrogen, hydrogen, helium, above 100 km (generally hard to see due to limitations of our vision against the night sky)
The movement of these electrons across the magnetic field creates shifting colours. Moving electrons causes currents which can reach 20 million Amps at 50,000 V. (To provide some context, a typical circuit breaker in North America will disengage when current flow exceeds 15-30 Amps at 120 V. That’s a lot of electricity!) It’s no wonder the Aurora is sometimes known as a lightning storm without the thunder.
The lesser known cousin of the Northern Lights, the Southern Lights, or Aurora Australis. can be seen in Southern New Zealand, Argentina, and Antarctica. It’s less popular, simply because there is much less landmass near the southern magnetic pole than in the north, so it’s much harder to see them.
The science is fascinating, but there is something magical about just calling them fox fires. Until I get to see the fox fires in person, I’ll just have to make do with this LIVE CAM currently in Yellowknife: AuroraMAX