The Northern lights are caused by solar wind hitting the magnetosphere. They are easiest to see far up North in the winter. In the south hemisphere there is the Aurora Australialis. The Aurora Borealis is more famous even though they look the same. The aurora Borealis are best seen when solar wind is coming in more commonly than normal. The colors seen are caused by different gas's reaction to the solar wind materials.
The best place to view the lights is in Greenland. In order to get to Nuuk, Greenland, you have to take a plane. One good place to view the lights is North east of the city in the mountains, you can't miss them. In Viking folklore, the Northern lights are depicted as a flame in the sky.