Aurora Pictures (Northern Lights)
My son took these pictures of the Aurora on May 11, 2024. (He actually has a PhD in astrophysics, but this was just taken with his iPhone after watching the Oilers-Canucks playoff hockey game that night).
The Aurora or Northern Lights are a product of the solar wind, which is a flow of subatomic particles coming off of our sun and intersecting the Earth's atmosphere. When that flow is heavy, such as after a solar storm or solar flare, we get the aurora. Usually, you have to be fairly far up in latitude to see it, but in some cases it can be seen quite far south.
When charged particles (electrons=negative, protons=positive) encounter the Earth's magnetic field they interact with it, traveling along the Earth's magnetic field lines, which extend out into space around the Earth (the nickel-iron core of the Earth acts like a dipole since charges flow within it). On the night side, the magnetic field lines stretch far away and can become discontinuous, with the line sort of snapping back towards the Earth, carrying the charged solar wind particles with it. They can then be accelerated into the Earth's atmosphere, where they can interact with gases there.
The colours and intensity of the light depend on the energy and charge of the particles, which particular gas with which they collide and the altitude of the collision. Reds are usually produced far up (240-400 km), greens more intermediate (100 to 240 km) and blues lower down (80-100 km). For references "space" is usually considered to start at about 100 km, though there is a very tenuous atmosphere at these altitudes. Collisions with nitrogen are generally red, violet or blue. Oxygen is usually green or yellow. The vast majority of the atmosphere is made of these gases (with traces of others such as argon, CO2, etc.).
Charged particles in motion within the Earth's magnetic field can create induced currents that affect communications and electrical infrastructure. So, they are pretty but can be very disruptive. I guess you could say that about other pretty things too. :)
In the photos below, I have matched the original iPhone picture with one that was enhanced with the image processing program GIMP, via fiddling with the exposure and contrast setting, as well as some strategic cropping. But nothing is added, just enhanced.
1 -Violets and Greens - nitrogen and oxygen.
2 - Mostly Green with hints of Violet (mostly oxygen, a bit of nitrogen).
3 - Mostly Green, hint of Violet again. Sort of a curtain effect.
4 - Similar to above. the pictures were taken in a neighborhood park, thus the houses, proving that these were pretty impressive Northern Lights, even in the middle of a rather large city (million plus).
5 - Mostly Green, hint of Violet again.
6 -Violets and Greens, a rather psychedelic effect.
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If you like Northern Lights and Magnetic Anomalies, you should read this short story (soon to be a novel):
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