Mother Nature put on her own light show at the South Pole last month when atmospheric halos appeared before researchers, construction workers and a visiting TV crew. The halos were caused by the reflection and refraction of sunlight by ice crystals in the atmosphere.Within about 30 minutes the witnesses observed at least 24 halos overhead. An expert at the South Pole station, operated by the National Science Foundation, said the January sighting could set a record for the most halos visible from one spot. Multiple sightings were also reported there in 1986 and 1990.