For example, during the huge disturbance in March 1989, there were aurorae seen over northern Australia as far north as Exmouth in Western Australia. At the same time in the northern hemisphere, aurorae were seen over Texas. Aurorae are caused by high energy particles from the sun entering the magnetosphere of the earth and following the magnetic field down to polar regions. Here, they strike molecules of air in the upper atmosphere at around 100 kilometres causing the atoms to radiate light. This radiation gives aurorae their characteristic colours and the patterns of the magnetic fields give them their interesting shapes.
Auroral display appear in many forms including bands, arcs, rays and sheets.
They may vary considerably in shape and brightness over timescales from seconds to minutes. Aurorae are a beautiful sight and much of this beauty has been captured in a series of photographs by David Miller. In the following we show some of his spectacular photographs. More photographs will be added in coming months. More information about the photographs and their use can be obtained directly from David Miller at the following address.