2008 TC3 wasn’t a particularly interesting asteroid. It wasn’t very big (only 1-5 metres wide) and it didn’t really stand out as being special (if it was special, we didn’t have any time to realise it anyway). If 2008 TC3 was in a crowd of other asteroids you wouldn’t have picked it out. In fact, it was that “normal” that it wasn’t named, it just kept its original asteroid designation number. 2008 TC3 was an ordinary piece of space rock in an extraordinary situation.
This was the first ever asteroid that astronomers were able to track and predict (with high precision) where and when it was going to hit Earth. Sure enough, astronomers using the Mt. Lemmon telescope in Arizona as part of the NASA-funded Catalina Sky Survey for near-Earth objects discovered 2008 TC3 before it hit Earth, enabling us to be forewarned a whole six hours before impact. If the object was any larger, astronomers will have (for the first time) been able to warn people on the surface, thus saving lives.
In fact, asteroid 2008 TC3 is so special that I’m going to give it an unofficial name: Asteroid Brian*.
This morning, Brian hit the Earth’s atmosphere at 2:43 UTC above the African nation of Sudan, exploding into a fireball. It arrived three minutes earlier than expected. The only observation of Brian’s impact comes from an infrasound array in Kenya (pictured top), and as a consequence, it is thought the object hit with an energy of between 1.1 and 2.1 kT of TNT. Most of Brian will have vaporized, with only small pieces of the rock hitting the ground as meteorites.
No images of impact have been revealed, probably due to the remote location, but airliner pilots were on the look-out for any bright flashes in the African skies:
“Half an hour before the predicted impact of asteroid 2008 TC3 [a.k.a. Brian], I informed an official of Air-France-KLM at Amsterdam airport about the possibility that crews of their airliners in the vicinity of impact would have a chance to see a fireball. And it was a success! I have received confirmation that a KLM airliner, roughly 750 nautical miles southwest of the predicted atmospheric impact position, has observed a short flash just before the expected impact time 0246 UTC. Because of the distance it was not a very large phenomenon, but still a confirmation that some bright meteor has been seen in the predicted direction.” – Jacob Kuiper, General Aviation meteorologist at the National Weather Service in the Netherlands.
Although small asteroids the size of Brian hit the Earth once every few months, this is the first time we have been able to predict the future impact of a meteoroid with Earth. An amazing achievement…
*Although “Brian” would be a noble name for an asteroid, I doubt the International Astronomical Union would accept my suggestion… or will they…?