The aurora australis is a light display that can be seen in the night sky over Antarctica, during the winter. It is also referred to as the Southern Lights. In the northern hemisphere, this same phenomenon is referred to as the Northern Lights or the aurora borealis. The Northern Lights can be seen in the Arctic Circle, over northern Canada, Alaska, Russia and Scandinavia.
Auroras are named for the Roman god of dawn, Aurora, which is the Latin word for dawn. Australis is the Latin word for of the South, while borealis is the Greek word for the North wind. Aurora australis quite literally means dawn, or light, of the south. Both auroras have similar properties, and only differ in where they can be viewed.
An aurora is the bands of colored lights that can be seen in the sky. The light is caused by charged particles, electrons and protons, colliding with other molecules in the upper atmosphere around the Earth. In particular, they collide with nitrogen and oxygen. Some of the energy that results from these collisions is emitted as light, or photons.
Red, green, and sometimes blue light is seen during the aurora australis. When the charged particles collide with oxygen, either a green-yellow or deep red colored light is produced. The green-yellow is the most commonly seen of the two. Collisions with nitrogen cause blue light to be displayed as part of the aurora.
The charged particles originate at the Sun and are referred to as the solar wind. Due to continuous reactions occurring on the Sun, these particles are constantly being released and leave the Sun at speeds from 300 to 1,000 kilometers per second, or about one million miles an hour. At these speeds, the particles can reach Earth in a couple of days.
Earth’s magnetic field deflects these particles when they reach the upper atmosphere. The charged particles are constrained by the magnetic field lines and travel around the Earth. The electrons and protons travel down the field lines towards the north and south magnetic poles of the Earth. At the poles, the magnetic field is closer to the surface of the Earth, allowing the charged particles to interact with other molecules in the atmosphere.
The best time to view an aurora is during a high level of activity on the Sun. The higher the levels of activity, the more charged particles are released and sent toward Earth. The aurora australis can only be viewed between March and September, as during the rest of the year, the South Pole has sunlight for 24 hours a day. When the aurora australis is visible, it usually lasts for about 15 minutes to half an hour. It can continue to appear ever two to three hours.