The Water Planet: Origin of Life on Earth  

There is no definitive evidence that proves beyond a doubt where water originated. But wherever it came from, water did eventually cover more than two-thirds of Earth's surface. The implications of this for the formation of life on planet Earth were...
Subject: nitrogen
Transcript: life? Two reasons. One, life is made out of chon-- Carbon, hydrogen, oxygen, nitrogen. Water is made out of two Of those elements-- hydrogen and oxygen