But what causes auroras in the first place?<\/p>\n\n\n\n
The Physics behind Auroras<\/h2>\n\n\n\n
The physics behind the auroras is as fascinating as the aurora itself. Openings in the Sun\u2019s atmosphere allow charged particles – electrons and protons, to flow out. These charged particles travel at extremely fast velocities towards the Earth, carried by what we call solar winds. Now the Earth happens to have a magnetic field of its own – the same field that helps align our compasses. This magnetic field acts as a barrier for the planet, and deflects most of the charged particles. <\/p>\n\n\n\n
At the poles however, the magnetic field is weaker. This allows the charged particles to breach Earth’s atmosphere. When these charged particles interact with the gaseous particles in our atmosphere, an aurora shows up in our skies. The charged particles have enough energy to knock off the gas atoms in our atmosphere – this causes the atoms to give off light, and eject more charged particles. Result? Aurora.<\/p>\n\n\n
![\"Auroras,](\"https:\/\/entropymag.co\/wp-content\/uploads\/2024\/01\/auroradiagram.png\")
The variation in colours of auroras is observed based on the type of gaseous particles, usually oxygen. The color depends on the gas atom that’s knocked off in the atmosphere:<\/p>\n\n\n\n
- \n
- Green – oxygen, 0 – 150 miles altitude<\/li>\n\n\n\n
- Red – oxygen, 150+ miles altitude<\/li>\n\n\n\n
- Blue – nitrogen, 0-60 miles altitude<\/li>\n\n\n\n
- Purple\/violet – 60+ miles altitude<\/li>\n<\/ul>\n\n\n\n
The red coloured aurora is formed at higher altitudes where the concentration of oxygen is less. This is the reason red coloured aurora is very rare. To add to that, our eyes are less sensitive to this wavelength making it more difficult to observe it. With reducing altitude, oxygen concentration spikes up – this causes the more common green coloured auroras.<\/p>\n\n\n\n
Interpretations<\/h2>\n\n\n\n
The lights obviously provide a sense of awe, but unsurprisingly, they’ve also become a source of superstition. Cave paintings in France dating back 30,000 years feature aurora illustrations. Before humans figured out how auroras work, different civilisations ended up with varying interpretations of the lights. The Inuit of Alaska considered the lights as the dancing souls of seals, salmon and beluga whales. The Swedes and Scots considered the lights just as merry dancers. To the Chuvash people of Central Asia, it was the deity called upon to ease women through their labour pains. The Lakota tribe from North America considered it to be spirits of the future generations waiting to be born.<\/p>\n\n\n
\n![\"Cave](\"https:\/\/yaabot.com\/wp-content\/uploads\/2015\/11\/yaabot_aurora_3.jpg\")
<\/a>Cave painting from the Cro-Magnon era (30,000 B.C.), considered the oldest associated with auroras. Source: NASA.<\/figcaption><\/figure><\/div>\n\n\n Even after the scientific reason as to why the lights appear has been identified, people are still known to follow popular beliefs. Japanese couples visit Northern Canada believing children conceived under the lights will be more fortunate. Scandinavian fishermen consider the lights as an omen of abundance.<\/p>\n\n\n\n
Can we see the true colours of the lights?<\/h2>\n\n\n
\n![\"Images](\"https:\/\/yaabot.com\/wp-content\/uploads\/2015\/11\/yaabot_aurora_4.jpg\")
<\/a>Images of auroras captured by photographer Mike Taylor show that what the eye sees (top) lack the color and vibrancy of the true colors revealed by a camera (below) – Source<\/a><\/figcaption><\/figure><\/div>\n\n\n If you’re heading out to witness auroras first hand based on the pictures you’ve seen all over the internet, you may be in for some disappointment. In real life, the colours that we perceive when we view the lights are generally shades of grey and white. At the same time if a photo of the lights is captured using a DSLR, multiple different colours – reg, green and blue – are captured. <\/p>\n\n\n\n
To understand why this happens, we need to delve in deeper into the functioning of the human eye. There are two types of cells in our eyes – cones and rods. Cone cells detect colour in bright light, while rod cells detect fainter colours in the dark which are viewed as black, white or shades of grey. Since we observe aurora lights only at night, our eyes can’t perceive the vibrant colours, limiting our perspective to shades of grey.<\/p>\n\n\n\n
The dynamic range of a DSLR camera is much higher than our human eye. Additionally, all the gorgeous photos we see are thanks to the increased exposure time on these cameras, which help reveal the true colours of these auroras.<\/p>\n\n\n\n