Auroras light up the sky over Darfield, New Zealand, on July 10, a few days after a huge flare erupted from the sun.
Auroras are created when charged solar particles slam into Earth's magnetic field and get funneled poleward. The particles collide with molecules in our atmosphere, transferring energy and making the air molecules glow.
Green light, like the kind pictured here, is the product of the particles' collision with oxygen. The more reddish swaths are caused by interaction with nitrogen.