![artistic rendering of early earth landscape](images/media/library_005_lg.jpg)
About two billion years ago, the methane haze cleared, and the sky turned blue, reflected in the water below. Illustration by Mary Parrish © Smithsonian Institution
About two billion years ago, the methane haze cleared, and the sky turned blue, reflected in the water below. Illustration by Mary Parrish © Smithsonian Institution