Aurora

In my opinion there is no greater natural spectacle than the Aurorae. I first saw them while standing on a frozen lake in the north of Finland. We had left our little fire hut on the shore because a very faint green glow could be seen over the treetops. As we watched, a wall of green swept silently across the sky, flecked with pink lines. When you see a picture of the aurorae you do not get the sense of motion or scale. The aurorae occur when particles, ejected on the solar wind, are channeled by the Earth’s electromagnetic field into the atmosphere. As the particles strike the atmosphere they ionize atoms which then release light. Some people report hearing a crackling sound when aurorae are particularly intense, but this has never been confirmed.