When a fireball whizzed over Florida on Jan. 24, more than a hundred witnesses reported spotting the flare on the American Meteor Society’s website. Within a week, Mike Hankey, an amateur meteorite hunter based nearly a thousand miles away near Baltimore, was holding a muddy chunk of the space rock he found near a swamp.

“With A.M.S. we are connecting the sky to the ground,” Mr. Hankey, 43, said, referring to the fireball tracker he manages for the American Meteor Society, a nonprofit organization that monitors fireballs and meteor showers, when he’s not running a software development business. “People are seeing this object in the sky and then a few weeks later they are holding it in their hands.”

Since last October, citizen scientists like Mr. Hankey have uncovered fragments from at least three different fireball sightings using data collected and analyzed by the society. For his Florida hunt Mr. Hankey reconstructed the trajectory of the fireball from the eyewitness reports and then compared it with Doppler radar readings he received from a colleague at NASA. Doppler radar are normally used to measure rain clouds and weather patterns but on occasion they catch a meteor’s path through the sky. Using both tools, Mr. Hankey pinpointed where the fireball’s fragments could have fallen.