Sky-watchers throughout the region had an opportunity Tuesday to see a fireball light up the nighttime with the full brilliance of the sun. But the audience was limited at 4:50 a.m. on a bitter cold morning.
But NASA produced video of the notable meteor. A 500-pound space rock, or meteoroid, entered the atmosphere to become a meteor that tracked west to east across southwestern Pennsylvania, producing a sonic boom. That means it likely had enough mass to deposit meteorites in an area northeast of Kittanning near the Clarion County border.
Mike Hankey, operations manager of the American Meteor Society, said the sonic boom and meteor explosion produced a burst of light that, for an instant, was comparable in size to the sun.
The sonic boom, measured on four seismographs, indicates the meteor had sufficient mass and speed to reach deep into Earth’s atmosphere before exploding into numerous meteorites, likely ranging in size from grapes to golf balls.
“The material is superdense and contains metal. Even something smaller than a baseball can be about a kilogram [2.2 pounds],” he said, adding that the original mass was about 2 feet in diameter, or about the size of making a ring with one’s arms. “That’s pretty big. It was a nice-size boulder.”
Typically, a large portion of the meteor is lost to light and heat in the atmosphere that produces the fireball. So only 10 percent of larger meteors, or about 50 pounds in this case, potentially reach Earth. A meteor has to be sizable to produce meteorites before being vaporized.
The most important indicator of size is the sonic boom. “It’s really all about the booms,” Mr. Hankey said, adding that the AMS received “a good number of boom reports,” mostly from the Pittsburgh area. “It’s a good candidate for a [meteorite] dropping event.”
The likely landing spot for meteorites would be 2 miles wide and 10 miles long in northern Armstrong County just south of Redbank Creek, which serves as the border with Clarion County. That would put the 20-square-mile area about four miles due north of the village of Templeton.
Meteoroids are space rocks that become meteors once they enter Earth’s atmosphere, with the mass and speed generating the heat and light, Mr. Hankey said. A person can see several meteors — also known as fireballs, falling stars or shooting stars — in the nighttime sky every hour. Most burn out in the atmosphere. A meteor of this size appearing in a populated region occurs worldwide only about once a month, he said.
Mr. Hankey said only a few dozen people hunt for meteorites, including him, with Geology.com valuing a 1-pound meteorite at about $400, with most valued at about $1 a gram.
NASA cameras on the roof of the Allegheny Observatory in Riverview Park in the upper North Side captured a video of the fireball piercing the sky, building in size before exploding.
Lou Coban, who manages the observatory, said that NASA cameras, through triangulation, can provide a good estimate of the meteor’s mass, direction and general landing site.
Larger meteors typically lead to calls to the observatory, which occurred to a limited degree after the Tuesday meteor event. “If it were summertime, we would have gotten a ton of calls,” he said. “But it’s winter, freezing cold and 4:50 in the morning. Not many people saw it.”
Still, he said, the meteor was a unique spectacle in local skies.
“Actually, it is rare to see something that bright,” Mr. Coban said.
“I’ve seen many, many meteors or fireballs, but it is pretty rare to see one that big.”
David Templeton: dtempleton@post-gazette.com or 412-263-1578.
First Published: February 18, 2015, 7:52 p.m.
Updated: February 19, 2015, 3:53 a.m.
