There is a theory that was once considered to be quite controversial, so much so that scientists labeled it absurd. It claimed that for millions of years the our planet Earth was covered entirely by ice, every inch smothered by nearly a one kilometre thick sheet. The temperatures would have been -40ºC all over, even in the tropic regions located along the equator. If this was indeed the case then virtually nothing could survive such an extreme environment.
For over 50 years a group of scientists have been trying to prove this incredible theory and now it seems the scientific community is slowly coming around to the idea as there are some tantalising geological clues that show this theory may be true, the only problem seems to be the fact that the theory of a Snowball Earth defies the laws of nature.
With many mysteries now becoming solved those in the know are starting to believe that Earth was in fact completely frozen over for a period of about 10 million years and then warmed up rapidly about 600 million years ago. It is thought that this sudden shift in climate gave rise to the evolution of complex life on this planet.