Washington: Astronomers are mystified over the bizarre breed of slow-moving meteors that are lighting up the skies this month.
Although the February’s fireballs - a term that describes meteors that appear brighter in the sky than Venus- are a well-known phenomenon but the astronomers are eager to know as to where they come from.
The strange deep diving, slow-moving fireballs vary in size from basketballs to buses and some are believed to have dropped meteorites.
Experts have asserted that the fireballs aren’t more numerous than normal, but their appearance and trajectory are odd.
“These fireballs are particularly slow and penetrating,” Discovery News quoted meteor expert Peter Brown, a physics professor at the University of Western Ontario, as saying.
“They hit the top of the atmosphere moving slower than 15 kilometers per second (33,500 mph), decelerate rapidly and make it to within 50 kilometers (31 miles) of Earth’s surface.”
The month’s fireball action started on Feb. 1, when a meteor lit up the skies over central Texas, putting up a dazzling show for people in the Dallas-Fort Worth area.
“It was brighter and long-lasting than anything I’ve seen before,” said eyewitness Daryn Morran.
“The fireball took about eight seconds to cross the sky. I could see the fireball start to slow down; then it exploded like a firecracker artillery shell into several pieces, flickered a few more times and then slowly burned out.”
The fireball was nearly as bright as the full moon, and was observed by NASA cameras in New Mexico, more than 500 miles (805 km) away.
It was most probably caused by an object 3 to 6 feet (1 to 2 meters) wide, NASA researchers said.
And the meteors have kept coming, well into February.
“This month, some big space rocks have been hitting Earth’s atmosphere,” said Bill Cooke of the Meteoroid Environment Office at NASA’s Marshall Space Flight Center in Huntsville, Ala.
“There have been five or six notable fireballs that might have dropped meteorites around the United States.”
Until now in February, NASA’s All-Sky Fireball Network - which presently consists of six cameras set up in Georgia, Alabama, Tennessee and New Mexico - has captured about half a dozen of these strange slow-moving, deep-diving fireballs.
Cooke has analyzed their orbits and determined where the strange meteors are coming from.
“They all hail from the asteroid belt, but not from a single location in the asteroid belt,” he said.
“There is no common source for these fireballs, which is puzzling.”
The “fireballs of February” have bewildered astronomers for decades.
Skywatchers first noticed an increase in the number of deep-penetrating, bright meteors during February back in the 1960s and ‘70s, Brown stated.
Research so far has been inconclusive, with some studies reporting a surge of these fireballs in February and others detecting no such trend, Brown said.
But NASA’s All-Sky Fireball Network could be successful in solving the mystery.
Cooke and his colleagues plan to keep adding up cameras to the network, increasing its coverage across North America.
“The beauty of our smart multi-camera system is that it measures orbits almost instantly. We know right away when a fireball flurry is underway -- and we can tell where the meteoroids came from,” Cooke added.
First Published: Monday, February 27, 2012, 15:08