TED-Ed

View full lesson: http://ed.ted.com/lessons/could-comets-be-the-source-of-life-on-earth-justin-dowd While comets were historically thought to be ill omens of war and famine, recent science has revealed that these celestial wonders actually contain amino acids, the building blocks of life on Earth. Justin Dowd explores the implications of this magnificent discovery. Lesson by Justin Dowd, animation by Justin Dowd.