According to Mythopedia
Towards the end of the Stone Age, the sky was ablaze with awe-inspiring forms not seen today. Dominant among these was a towering, life-like pillar of light stretching from near the horizon to high up into space – the tree of life, the world mountain, the ladder to heaven. This message is heard in virtually every ancient society on earth, but while this ‘world axis’ is familiar enough to scholars, little sense could be made of the stories. The most conspicuous feature of the ancient cosmologies also remained the most elusive.
From a modern scientific perspective, such traditional accounts no longer sound preposterous. Our growing knowledge of devastating events in recent earth history substantiates the possibility that prehistoric people witnessed a violent and prolonged display of high-energy auroras.
For the really big picture, see Plasma-Universe.