An explosion over the skies near the California-Nevada border early on Sunday has been confirmed to have been caused by a meteor the "size of a minivan," according to news reports.
The meteor, believed to have been a small asteroid, burned up spectacularly after slamming into the Earth's atmosphere at just under 34,000 miles per hour and generating energy equivalent to the explosion of 3.8 kilotons of TNT, according to Bill Cooke, director of NASA's Meteoroid Environment Office.
"Elizabeth Silber at Western University has searched for infrasound signals from the explosion," Cooke told SpaceWeather.com. "Infrasound is very low frequency sound which can travel great distances. There were strong signals at two stations, enabling a triangulation of the energy source at 37.6N, 120.5W."
The exploding meteor blew up several hundred miles west of San Francisco and reportedly shook houses across a wide swath around the Sierra Nevada mountain range from Central California to Reno, Nev.
"The energy is estimated at a whopping 3.8 kilotons of TNT, so this was a big event," he said. "I am not saying there was a 3.8 kiloton explosion on the ground in California. I am saying that the meteor possessed this amount of energy before it broke apart in the atmosphere."
The meteor is estimated to have been one of the largest to strike the Earth's atmosphere in recent years—larger than a three-meter wide object called Asteroid 2008 TC3 that blew up over Sudan in 2008, which was detected by astronomers at the Lemmon observatory in Arizona before it exploded.
The object that created a light show over the Sierras this weekend is estimated to have been between three and four meters wide with a mass of about 70 metric tons, Cooke said.
"The fact that sonic booms were heard indicates that this meteor penetrated very low in the atmosphere, which implies a speed of less than 15 kilometers per second [about 33,500 miles per hour]," he told SpaceWeather.com . "Assuming this value for the speed, I get a mass for the meteor of around 70 metric tons. Hazarding a further guess at the density of three grams per cubic centimeter, I calculate a size of about three to four meters, or about the size of a minivan."
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