The earth has been around for about four and a half billion years, according to the best estimates of climate scientists. But in its early life, the planet was much different than is it now. This week an article in Nature discussed how it has changed and estimated when conditions were first right for snow to form. Based on the characteristics of atmospheric composition determined from rocks and knowledge about when landforms first appeared, the authors estimated that conditions were first suitable for snow about 2.8 billion years ago. You can learn more about how they got to this conclusion and how snow affected the climate of the ancient planet at EarthSky here.

Source: Commons Wikimedia