* The snowball theory was created by Brian Harland in 1964.
*Scientist say that the snowball theory happen not just once but many times.
* Scientist say that our plant was once completely frozen over about 630 million years ago.
The Beginning of the snowball theory .
Evidence points to a reduction in so-called "greenhouse" gases in the atmosphere, principally CO2 (carbon dioxide) and CH4 (methane). This would have made the global climate colder, creating larger areas of ice and snow. Ice and snow reflect more Solar radiation than does bare ground or liquid water, which creates a "positive feedback". If the earth ever became approximately half-covered by ice or snow, the feedback would become self-sustaining and glacial ice would rapidly spread to the equator.