Hey Blog! I’m so sorry it’s been so long since I was doing weekly posts, life has got in the way and I wasn’t up to speed. I hope that even with my Environmental Management IGCSE Paper 1 Exam next week and Paper 2 Exam two weeks after, I will remain on top of my workload and continue posting. However, this post is about a natural phenomenon I saw last week for the first time – it’s the Northern Lights, the Aurora Borialis!
The Northern Lights are not to be confused with The Northern Lights by Philip Pulman, which I reviewed last year. The book says they are where the world is thin, made so by the solar wind, so you can see parallel universes. The scientists never mention the ability to see these other worlds, and though I looked, I couldn’t see any. Ah well. Still, they are amazing, with brightly coloured green, purple, and occasionally reddish, yellowish, and blueish lights covering the sky. They can be seen from space, from Earth, and they even occur on other planets. But why are they here in the first place?
Apparently, they aren’t light shining off the armour of the Valkyrie warriors coming to pick up Viking dead; spirits being taken to heaven; people engaged in a battle in the sky; a premonition of the French Monarchy being overthrown; foxes brushing mountains with their tales; or the fires of a deity; but instead a storm of solar wind. It occurs when a discharge of plasma through the Sun’s coronal holes draws some of the Sun’s magnetic field with it; this portion of solar wind (the continual plasma ejection which shines out of the Sun) amplified by the magnetic field around it then collides with our own magnetic field, Earth’s magnetosphere, the shield around Earth which protects us from solar radiation. The particles of plasma are deflected away from Earth, which makes the magnetosphere into a teardrop-like shape, but there is one small hole where solar particles can enter – a point where the magnetic field doesn’t ring around the Earth but flies outwards (look at a diagram of the force lines on a magnet), too far away to shield us – the poles! Particles are channelled down through the sky towards our poles, not poles in the ground like Pooh though, but rather magnetic poles. As the energy-rich particles hit our atmosphere, they ‘excite’ oxygen and nitrogen in the air; the electrons of these gases go into a higher orbit (a ‘hiccup’ one of my science teachers called it!) and as they come back down, they release the excess energy as light.
The light is coloured according to the gas, oxygen being most commonly green, and nitrogen being most commonly purple. The other colours are less common, but do occasionally show. A strong solar storm like the one just passed, which showed lights far south, only happens about once every 22 years, when the sun’s magnetic field ejects a large storm of charged particles – so watch out in 22 years for another showing of the northern lights!
All you need to make an aurora are:
- a magnetic field
- a stream of plasma
- and an atmosphere!
So, time for HEIAS Q&A:
- Why don’t we see it when we look at a magnet? We don’t have a plasma stream! (To all those people who have plasma cutters out there, I would love to come and put a magnet in your machine and see what happens!).
- How does it affect the poles? The equator gets hot, the poles do not, but you’ve just told me it only happens at the poles. The magnetic field only repels particles, not waves. Heat and light are electromagnetic radiation waves, not particles (although they’re also photon particles, really confusing and I do not understand them, but then no one does!). Particles are funnelled to the poles, whereas waves are not interfered with and so hit the equator.
- Could the magnetic shield be used to combat climate change? No, it only repels particles, not heat, and climate change is a change in heat. Awesome story idea though – Magnetic Protection, a climate change story!
- Would it occur if you held a lightsaber near a magnet? It depends. Some sources say lightsabers are made of plasma and therefore it would, yet some say they aren’t plasma swords but laser swords and therefore it wouldn’t. You haven’t got a lightsaber to test it on, have you?!
On Friday I managed to see the lights for the first time ever – it was the first time for Mum and Dad too, and they have been alive for a lot longer than I have! I was up till 10 hoping to see them, and then jumped out of bed at 11 to the news that they were very bright in the back garden! The lights shining over the shed was magnificent, green and purple and stripy across the sky; it was worth the late night even if I did sleep in in the morning! Picture quality was awful, so I can’t show you what they looked like, but the best description is a watercolour on the sky that never stayed in the same place for five minutes, constantly fading and reappearing, but so slowly you would never have known it had changed if you hadn’t looked away! I hope to see them again one day.