Its amazing how much one movie can act as a cultural touchpoint for an entire topic - even a topic as serious as defense of a planet. Popular media consistently use the 1998 movie Armageddon as a reference when talking about how we would destroy a civilization-ending asteroid. Thats despite the movies glaring scientific flaws, not the last of which is the likely size of the rogue comet that threatens the Earth. Planetary defense researchers at MIT were recently interviewed by the universitys media department as part of their 3 Questions series. One of the most important takeaways is that the size of any likely planetary impactor in our lifetime is going to be much smaller than the kilometer-sized behemoth that did in Bruce Willis character - but we could face a threat from a handful of them before the end of the century.