Most meteorites break off a larger, parent meteoroid well before entering our atmosphere. The Tagish Lake Meteoroid, however, plunged headlong into the stratosphere before shattering with more energy than thebomb that took out Hiroshima. The meteoroid itself was estimated to be 4 meters (13 ft) in diameter with a weight of 56 metric tons, large enough to wreak havoc in a large area if it had landed intact.
As it was, about 93 percent of the meteoroid was ablated, or vaporized, before it erupted into a fireball. It exploded about 40 kilometers (25 mi) above the Earth’s surface and sent thousands of meteorites clattering across the frozen surface of Tagish Lake in Canada. When NASA arrived to study the pieces, they had to cut blocks of ice out of the lake because the fragments were too deeply embedded to remove. Theentire lake had been perforated. After studying the meteorites, it was discovered that they had come from 773 Irmintraud, a minor planet (or large asteroid) that floats between Jupiter and Mars.