It appears that we have gotten much better at predicting when and where asteroids will impact on the Earth. A fairly large one just exploded over the Sudan recently and it was tracked and the impact was predicted by experts and several amateurs as well. From the Honolulu Star Bulletin
Asteroids routinely hit the Earth's atmosphere but the impact by one over northern Africa Monday was the first time astronomers saw one coming and accurately predicted the time and place it would hit, a University of Hawaii astronomer said yesterday.
The impact occurred at 4:46 p.m. Hawaii time Monday over northern Sudan. A colleague compared the asteroid, called 2008 TC3, with the size of a Volkswagen, he said."
These hit the upper atmosphere all the time but there is always the possibility that a really big one could be coming our way and it's good to know when and where. It doesn't chjange the fact that there isn't much we can do about it but tracking them is a good start.
Tholen said more than 500 observations were made of the asteroid approaching Earth by astronomers all over the world, primarily in Europe and western Asia.
"It was the first opportunity to really test the whole impact-prediction software system on a real object," he said, adding that it was 100 percent accurate.
There was one report of a visual sighting by a KLM Airlines pilot, but it was far from the impact location and merely saw "a streak of light," he said."
"These things happen every month or two and most of the time just go unnoticed, except people on the ground who see the fireball," Tholen said. "This time, astronomers saw it first and could predict the fireball. It was unique."