1/4 exposure time so 250 ms of light. the light is coming from all the light sources in the universe, plus the moon, plus the sun's rays refracting through the atmosphere which happens even at night.
The natural blue light is coming from the oxygen in the atmosphere but it's so overwhelming in that spot that it turns the light pure white. The red/orangish is coming from particulates and the green/red from aurora. My favorite part I think is the very bottom where you can see the blue light taper off and not overwhelm the camera sensor and you can see the aurora with it. I love this photo so much.
Probably my favorite photo ever now.