@CNN: This NASA animation shows the dramatic increase of near-Earth objects. See how many asteroids and comets have come close to Earth in the past 20 years. https://t.co/tityNsoZJC https://t.co/pj5SIxnUz4

@CNN: This NASA animation shows the dramatic increase of near-Earth objects. See how many asteroids and comets have come close to Earth in the past 20 years. https://t.co/tityNsoZJC https://t.co/pj5SIxnUz4