Asteroid 2008 TC3 Hits Sudan
Artist's impression of a meteorite entering the Earth's atmosphere (©Leonard Wikberg III)
Yes, it's true. An asteroid has hit the Earth. Again. This happens roughly 1.4 million times per day, but this one was bigger than usual - it exploded with the equivalent energy of approx 1,000 tonnes of TNT, or a small atomic weapon. That only happens about once every two weeks.
This is not particularly news-worthy. Almost nothing, if anything, will have reached the ground. It does not pose any kind of major threat to mankind, or even a minor one.
It is, however, the first time in history that an asteroid impact has been predicted before it occurred. That is perhaps a slightly disconcerting fact, considering the number of asteroids out there, and one very close to my areas of interest. Asteroids larger than this one, maybe 30-50m in size, would explode with enough energy to destroy a major city. These impact maybe once every 30-100 years, we don't really know for sure. The good news is that major cities only make up a tiny fraction of the Earth's surface, but it's still just a matter of time before a lot of people get killed if we don't do something about it.
Knowing when and where an asteroid is going to hit is the key here - giving time to evacuate the area. We're not talking about "global-killer" asteroids 1km across as you might find in a disaster movie, so evacuating a town/city should be enough to avoid major loss of life in such an event. That's what makes this event so interesting - simply that we knew it would happen.
ESA's first ATV the Jules Verne burns up on re-entry. Image Credit: NASA/ESA/Bill Moede and Jesse Carpenter
I haven't found a (good) picture of the fireball yet - hence the artist's impression yoinked from astroengine.com, though obviously it looked different from the ground. This pic on the left is also not a photo of the fireball, but is probably much closer. It was taken by NASA during the re-entry of the European freighter "Jules Verne" - the first ATV, who wanted to compare the way it broke apart on re-entry (intentionally) to the way asteroids do.
Incidentally, for those who want to know the difference but are afraid to ask...
An asteroid is a large rocky body orbiting the sun. A much smaller body is called a meteoroid. I confess, I'm not sure exactly where the boundary between these two lies. Once an asteroid/meteoroid enters the Earth's atmosphere, it becomes a meteor. If the meteor survives to the surface, the part that does so is a meteorite.
Today is a funky science news day :)