A few days ago, the Sun unleashed a blast of subatomic particles, a massive wave of plasma that swept out into space at speeds of millions of kilometers per hour. On Monday, October 24th, that coronal mass ejection slammed into the Earth's magnetic field, compressing it, and causing a secondary wave of particles to cascade down into Earth's atmosphere at high speeds. These particles struck molecules in the air,
ionizing them, which then glowed fiercely as electrons recombined with their parent atoms exciting the electrons in atoms, and when the electrons give up that energy the atoms glow.
In English? Tremendously bright northern lights! Check this out:
That was taken by photographer Eric Hines on the shore of Lake Michigan last night. You can see the glow reflecting in the water! Another photographer, Randy Halverson, took an amazing shot as well and said the aurorae were "insanely" bright, and on his website commented they were so bright it was hard to get them exposed correctly. Universe Today has a lot more pictures as well.
Aurorae were reported as far south as North Carolina and Arkansas! This was a big magnetic event, larger than we've seen in some time. It's already dying down, but you never know: there may be some activity tonight. It never hurts to go outside and look to the north. If you don't look, then you're guaranteed not to see anything.
Image credit: Eric Hines, used by permission