show. astronomers have taken these incredible pictures, the first time telescopes on earth spotted relatively small objects burning up in jupiter's atmosphere, what do they mean for us? michio kaku is a physicists professor and host of sci-fi science, physics of the impossible. what are we seeing there, those fire balls? >> this was a great week for asteroid hunters! last wednesday, not one but two asteroids threw right by the earth, first time in history and now for the first time in history, to vully verify two small impacts from jupiter, there's a lot of this in space. jon: several asteroids are not the one that -- that passed the earth were not by jupiter. >> they came within the moon, outside the limit of our satellites, that's how close they came, about 50 feet across, about 1 million pounds of rock. jon: what would have happened if they had actually hit earth's atmosphere?