Nova: Season 51, Episode 1

51 - 1: Ancient Earth: Birth of the Sky

Today, Earth is enveloped by a thin veil of gas, a narrow band of atmosphere that protects a world covered in lush green vegetation, deep blue oceans, and abundant life. But 4.5 billion years ago, Earth was a very different place: a hellscape of molten lava and barren rock, under relentless bombardment from meteors, and with no atmosphere whatsoever. So how did our familiar blue sky come to be? Breathtakingly realistic animations and a chorus of science experts reveal how the primordial inferno first gave rise to an orange-hued cauldron of toxic gasses that would be deadly to us today. Witness how the first drops of rain splashed down on the searing planet, setting the stage for the evolution of life. And discover how life itself helped create the air we all breathe today.