... Bad Astronomy . ... Movies . ... Bitesize Astronomy . ... The trailers started running in theaters many months before the movie came out, and I knew right away that "The Core" was ripe for a BA review. I remember distinctly that one line in the trailer said that the reversal of the Earth's magnetic field wipes out all life every 700,000 years. ... So they really blew it in the movie; they could have used real science to collapse the magnetic field, instead of the silliness of stopping the core. ...