Did a Comet Trigger The Great Chicago Fire? By Irene Mona Klotz, Discovery News The Great Chicago Fire of 1871 March 5, 2004 — Perhaps it was not Mrs. O'Leary's cow kicking over a lantern that sparked the Great Chicago Fire of 1871, which destroyed the downtown area and claimed 300 lives. New research lends credence to an alternative explanation: The fire, along with less-publicized and even more deadly blazes the same night in upstate Wisconsin and Michigan, was the result of a comet fragment crashing into Earth's atmosphere. The comet theory has been around — and most often discarded...