Giant California Fireball
Rocks From Giant Explosion Are Meteor Fragments
by Selin Gök, age 16
The average meteor enters the Earth’s atmosphere at a speed between 22,000 and 44,000 miles per hour. Meteors are faster than the speed of sound and create a sonic boom as they enter the atmosphere. These spectacular events are fascinating, but do not occur often.
One did last April.
Earlier this year, tiny meteorites were found in the Sierra foothills of northern California. These meteorites were the fragments of a meteor that exploded in a giant fireball with energy equivalent to a 5-kiloton explosion. In comparison, Hiroshima’s atomic bomb released 15 kilotons of explosive energy.
Tim Spahr, director of the Minor Planet Center at Harvard University, said that the friction between the rock and the air was so intense that parts of the rock vaporized instead of burning up.
A professor and expert in meteorites at UCLA’s Institute of Geophysics and Planetary Physics, John T. Wasson, reported that the total mass of each individual rock was about 10 grams, equal to the weight of two nickels.
Shockingly, the fireball was about the size of a minivan as it entered the Earth’s atmosphere. The meteor was seen from as far away as Sacramento, California, Las Vegas and northern Nevada. It weighed approximately 154,000 pounds, according to Bill Cooke, a specialist in meteors at NASA’s Marshall Space Flight Center in Huntsville, Alabama.
Robert Ward, an Arizona resident who hunts and collects meteorites from all corners of Earth, says he discovered the first piece of the meteorite on the edge of the town Lotus. After noticing that the meteorite had crusts formed from fusion during its entry into the atmosphere, Ward said he “instantly knew” that the meteorite was a rare type known as “CM”, or carbonaceous chondrite.
Don Yeomans of NASA’s Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, California finds the incident “exciting.” He says the possibility of an event that size might happen once a year and “…most of them occur over the ocean or an uninhabited area.”
[Sources: Associated Press; USA Today]