CAPE CANAVERAL, Fla. —
"Now that's pretty big. That's typically a couple times bigger than the normal influx of meteorites that create these fireballs," he said in an interview on NASA TV.
"These fireballs happen about once a day or so, but we just don't see them because many of them fall over the ocean or in remote areas. This one was an exception."
As the countdown for the asteroid's close approach entered the final hours, NASA noted that the path of the meteor appeared to be quite different than that of the asteroid, making the two objects "completely unrelated." The meteor seemed to be traveling from north to south, while the asteroid passed from south to north — in the opposite direction.
Most of the solar system's asteroids are situated in a belt between the orbits of Mars and Jupiter, and remain stable there for billions of years. Some occasionally pop out, though, into Earth's neighborhood.
NASA scientists estimate that an object of this size makes a close approach like this every 40 years. The likelihood of a strike is every 1,200 years.
The flyby provides a rare learning opportunity for scientists eager to keep future asteroids at bay — and a prime-time advertisement for those anxious to step up preventive measures.
Friday's meteor further strengthened the asteroid-alert message.
"We are in a shooting gallery and this is graphic evidence of it," said former Apollo astronaut Rusty Schweickart, chairman emeritus of the B612 Foundation, committed to protecting Earth from dangerous asteroids.
Schweickart noted that 500,000 to 1 million sizable near-Earth objects — asteroids or comets — are out there. Yet less than 1 percent — fewer than 10,000 — have been inventoried.
Humanity has to do better, he said. The foundation is working to build and launch an infrared space telescope to find and track threatening asteroids.