Image of the Day: Green Aurora from the ISS

ISS_aurora_australis
 

The ISS was a couple of thousand kilometers away from the green lights of the southern aurora when this shot was taken.The aurorae are usually between 80 – 160 km (50 – 100 miles) above the Earth’s surface. The green glow is characteristic of oxygen.

This aurora was probably caused by subatomic particles from an explosive event called a coronal mass ejection from the Sun five days earlier. The particles interact with our magnetic field, which channels them to the north and south poles. They slam into the air, ripping electrons off the atoms and molecules. When the atoms recombine, they give off light. 

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