Earth's magnetic field was pummeled by a double coronal mass ejection (CME) over the weekend, giving rise to more than 24 hours of geomagnetic storms and exceptionally beautiful northern lights. Here, astrophotographer Brad Goldpaint has captured a rare sight: a stunning pink aurora borealis.
Goldpaint snapped this photograph [click here for more views] from the rim of Oregon's scenic Crater Lake. (Spaceweather.com reports aurorae were spotted at latitudes as far south as Utah!) According to BadAstronomy's Phil Plait, it's rare to see a pink aurora looking so vibrant, especially on its own. More typical hues include green, red and blue, and are usually emitted by O, O2 and N2 in Earth's upper atmosphere:
If you have a source of red and blue light, these can combine to make something look magenta or pink, like in the diagram here. I strongly suspect that's what's going on here; we're seeing a combination of red and blue light emitted by nitrogen molecules high over the Earth, and our eyes see that balance as pink. Cameras are designed to see colors much the way our eyes do, so the aurora looks pink in pictures as well.