APNewsBreak: Fireball remnants likely in Calif.
Topics: From the Wires, News
This image provided by NASA's Jet Propulsion Laboratory shows a meteor over Reno Nevada Sunday April 22, 2012. The former space rock-turned-flaming-meteor entered Earth's atmosphere around 8 a.m. PDT. Reports of the fireball have come in from as far north as Sacramento, Calif. and as far east as North Las Vegas, Nev. Bill Cooke of the Meteoroid Environments Office at NASA's Marshall Space Flight Center in Huntsville, Ala., estimates the object was about the size of a minivan, weighed in at around 154,300 pounds (70 metric tons) and at the time of disintegration released energy equivalent to a 5-kiloton explosion. (AP Photo/Lisa Warren, NASA/JPL)(Credit: AP)RENO, Nev. (AP) — Tiny meteorites found in the Sierra foothills of northern California were part of a giant fireball that exploded over the weekend with about one-third the explosive force of the atomic bomb dropped on Hiroshima in World War II, scientists said Wednesday.
The rocks each weighed about 10 grams, or the weight of two nickels, said John T. Wasson, a longtime professor and expert in meteorites at UCLA’s Institute of Geophysics and Planetary Physics.
Experts say the flaming meteor, dating to the early formation of the solar system 4 to 5 billion years ago, was probably about the size of a minivan when it entered the Earth’s atmosphere with a loud boom early Sunday. It was seen from Sacramento, Calif., to Las Vegas and parts of northern Nevada.
An event of that size might happen once a year around the world, said Don Yeomans of NASA’s Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, Calif. “But most of them occur over the ocean or an uninhabited area, he said.
“Getting to see one is something special,” he said. He added, “most meteors you see in the night’s sky are the size of tiny stones or even grains of sand, and their trail lasts all of a second or two.”
The meteor probably weighed about 154,300 pounds, said Bill Cooke, a specialist in meteors at NASA’s Marshall Space Flight Center in Huntsville, Ala. At the time of disintegration, he said, it probably released energy equivalent to a 5-kiloton explosion — the Hiroshima bomb was 15 kilotons.
“You don’t often have kiloton rocks flying over your head,” he said.
The boom, another expert said, was caused by the speed with which the space rock entered the atmosphere. Meteorites enter Earth’s upper atmosphere at somewhere between 22,000 miles per hour and 44,000 miles per hour — faster than the speed of sound, thus creating a sonic boom.
The friction between the rock and the air is so intense that “it doesn’t even burn it up, it vaporizes,” said Tim Spahr, director of the Minor Planet Center at Harvard University.
Wasson said one meteorite was found near the town of Coloma, about 35 miles northeast of Sacramento. “I’m sure more will be found, I’m hoping, including some fairly big pieces,” said Wasson.
“The fact that two pieces already have been found means one knows where to look,” he said.




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