Imagine a traveler from outer space, hurtling through the atmosphere of a bright, blue planet to land upon a world populated by strange, multi-tentacled creatures."A fall," explains Philipp Heck, associate curator of the Pritzker Center, "is an event in which the arrival of a meteorite is observed and recorded."The museum now houses the Robert A. Pritzker Center for Meteoritics and Polar Studies, with a collection that includes more than 15,000 meteorites from over 1500 falls.At the time of the World's Columbian Exposition in 1893, the collection of curiosities that would become the Field Museum included 170 meteorites.The stone is at Chicago's Field Museum of Natural History, one of four unusual slabs in a recently opened display of meteorites.This allows fragments to be identified with that event.It sounds like something from the pages of a science fiction novel, but it's a true story and it's written in stone.