Last night, I happened to be outside late and saw the Aurora Borealis for the first time. They weren't extremely bright, and looked like a banded green fog floating in the sky. It sparkled and morphed, some bands getting brighter and more distinct while others faded. Unfortunately, it wasn't bright enough to get a picture of.
[Science] Auroras are caused by the collision of solar wind particles with photon emissions in the Earth's upper atmosphere. Solar wind is the constant outflow of ions from the sun, and is funneled by the Earth's magnetic fields which carry them toward the poles and accelerate them. When the ions in the solar wind collide with the photons in the atmosphere, energy is released in the form of light. Interestingly, different types of atoms create different colors; since the one I saw was green, this was most likely the result of oxygen atoms. Auroras tend to be more frequent and brighter during the intense phase of the solar cycle when coronal mass ejections increase the intensity of the solar wind. [/Science]
