The aurora borealis, also known as the northern lights, is a natural light display in Earths sky, predominantly seen in high-latitude regions. The southern counterpart, the aurora australis or the southern lights, has features almost identical to the aurora borealis and changes simultaneously with changes in the northern auroral zone. Auroras occur when charged particles (electrons and protons) collide with gases in Earths upper atmosphere, producing tiny flashes that fill the sky with colorful light. Oxygen gives off green and red light, while nitrogen glows blue and purple. The aurora borealis is visible from areas around the Arctic such as Alaska, the Canadian Territories, Iceland, Greenland, Norway, Sweden, Finland, Scotland, and Siberia. On rare occasions, it can be seen as far south as the Mediterranean and the southern states of the US. The northern lights are generated when the solar wind, which is a stream of charged particles ejected from the sun, slams into Earths ionosphere, creating a phenomenon called aurora. The solar wind interacts with gases in Earths magnetic field, generating magnificent auroras. The more active the sun is, the more stunning the auroras will appear on Earth.