The meteor fragment is peppered with gray, white and reddish minerals, though one side is covered in what scientists called a “fusion crust” – a layer of dark material forged during the meteor’s fiery passage into Earth’s atmosphere. It weighs just 0.2 ounces (7.5 grams) and is about 2 inches (5 cm) long and less than an inch wide.
A camera mounted to a campus building at the University of Wisconsin-Madison caught the Wisconsin meteor’s explosive demise. The meteor’s sonic boom and explosion were also seen and heard by numerous witnesses, and sparked frantic 911 emergency calls across six different states, according to the Near-Earth Object Office at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif.
When the meteor exploded, it unleashed as much energy as the detonation of 20 tons of TNT, NASA scientists said. Their analysis found that the parent meteor was about 3.3 feet (1 meter) wide before it blew apart.
The first reported piece of the space rock was discovered by a Wisconsin farmer Thursday morning and brought to the University of Wisconsin-Madison for analysis.