February known as month for meteors
Fireballs the size of the one seen in central Russia are relatively rare, but are more expected when February rolls around.
"Smaller meteor fireballs are actually quite common, and curiously enough, the frequency of meteor fireballs is typically 10 percent to 30 percent higher in February than in other months for reasons that are unknown," said Dr. Jody Wilson, a research scientist at the University of New Hampshire's Space Science Center.
The so-called "Fireball February" phenomenon has been known since the 1960s, Wilson said.
It proved frightening Friday when countless video cameras and others mounted on car dashboards captured stunning images of a 10-ton meteor streaking across the Russian sky. The fireball that left a white trail hanging in the sky created an intense sonic boom that blew out windows and caused other building damage, leaving more than 1,000 people injured.
The meteor mayhem came on the same day that a 150-foot-wide asteroid passed dangerously close to Earth at 2:24 p.m. The asteroid was not believed to be linked to the Russian meteor.
"Simply based on the direction the fireball was traveling over Russia, which was approximately north to south, it had to have been in a very different orbit from (the asteroid), which is flying by the Earth in an approximately south to north direction," Wilson said.
The Russian meteor created panic and renewed fears of an end-of-the-world event just like one in 1908 that hit Siberia, flattening trees over 800 square miles and sending people running to holy shrines and monasteries to pray.
Wilson said the amount of damage caused by impacting meteorites depends mostly on the size of the meteoroid.
On any given night, Wilson said one can see several harmless meteors in the sky per hour caused by falling objects that are smaller than a grain of sand.
"At the other extreme, a 10-mile wide asteroid hitting the Earth can cause a global mass extinction such as the one that killed the dinosaurs," he said.
Wilson said 10-foot-wide objects - roughly the size of the Russian meteor - hit the Earth about once every year.
Life-threatening impacts are rare, and while they do happen, "there is so much uninhabited land and ocean on the Earth that it's more likely they will hit where nobody even sees them."