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Asteroids - Worlds That Never Were
Asteroids wiped out the dinosaurs and may be back for us but they also built the Earth and may have brought life to its barren surface. Asteroids will shape our future as much as our past and scientists are striving to unlock their secrets.
Aired: Aug 22, 2012 Genre: DocumentaryDuration: 42m Rating: 4.5 Country: United States of America Production: Discovery