What is the aurora?
The aurora appears as lights in the sky which are given off by atoms and molecules in the upper atmosphere when they are hit by high energy electrons.
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Where can we see the aurora?
The aurora can be seen best along the belt which connects central Alaska, the Great Slave Lakes (Yellowknife) in Canada, the southern tip of Greenland, Iceland, and the northern tip of Scandinavia.
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Can we see the aurora in the Southern Hemisphere?
The aurora in the southern hemisphere is known as the aurora australis. It is almost a mirror image of the aurora borealis.

Why does the aurora show different colors?
Different atoms and molecules in the upper atmosphere give off different colored lights. Atomic oxygen gives off greenish and red light. Molecular nitrogen gives off pinkish light.
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Why does the aurora move?
The aurora appears where beams of high energy electrons penetrate the upper atmosphere. As the beams move, the aurora moves.
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Why can we see the aurora on
cold nights, but not on warm nights?
The aurora occurs well above the altitude of clouds. On cold nights, the sky tends to be clear so that the aurora is visible. Warm nights tend to be cloudy and the clouds hide the aurora.

Can astronauts see the aurora from
the space shuttle?
Yes. The space shuttle flies at an altitude where the aurora is present. Astronauts say that it is spectacular to fly through the aurora.

The aurora seen from the space shuttle

Does the aurora produce a sound?
Technically it should be impossible to hear the aurora from the ground because the lowest edge is 60 miles (100km) away and the atmosphere there is too thin to transmit sound waves. However, reports of whooshing and crackling noises associated with active aurora persist and groups in Denmark and Finland claim to have recorded sounds. A number of theories regarding the perception of auroral noises abound.

Is the aurora harmful?
The aurora can cause a variety of problems. It can disrupt radio communications, damage satellites, and disrupt power stations and power lines resulting in power outages. The high energy electrons that produce the aurora may be hazardous to astronauts in space so they should remain in the spacecraft when it flies through an aurora. Here on Earth's surface we are safe. We live and travel in only the first 14km (8 miles) of Earth's atmosphere, nearly 100km (60 miles) below the aurora. Because of the protective role of the atmosphere, the aurora and the high energy electrons that produce it (under normal conditions) pose no known health risks such as those from radiation or electric shock.