Sutter’s Mill 
An unusual hailstorm struck California’s El Dorado County one year ago this week. And like most modern-day storms, it was tracked by radar. That helped scientists quickly find some of the hailstones - pieces of an asteroid that exploded as it hurtled through the atmosphere.
The asteroid hit Earth on April 22nd. It created a brilliant fireball that was visible across hundreds of square miles, as well as a powerful shock wave that rumbled through the mountains.
Scientists used video shot from a couple of different locations to triangulate the fireball’s path. They also used still photos, audio recorded by listening stations, and something that had never been used before: weather radar. Three radar stations recorded “echoes” from small bits of rocky debris as they fell toward the ground.
With that information, scientists and others headed for the area near Sutter’s Mill, where the great California gold rush started in 1848.
They found the first tiny meteorites just two days after the fireball. And it was a good thing they did, because the bits of rock contained compounds that are destroyed by any contact with water. Just after they were discovered, it rained all across the area, contaminating the remaining meteorites.
In all, close to a hundred small pieces of the Sutter’s Mill meteorite have been discovered. They’ve helped scientists piece together the asteroid’s origin, its orbit, and its history - important insights from cosmic hailstones.
Script by Damond Benningfield, Copyright 2013