Yesterday was a significant day in astronomy. Yesterday evening, Tucson time, an asteroid 5 meters across streaked across the sky of Chad, Egypt, and Sudan. This kind of event happens routinely, an object 5 meters across encounters our planet about once every few months. What made this rock, 2008 TC3, significant was that for the first time, ever, an asteroid was discovered on a collision course with Earth. We observed it as it approached our planet, and according to some early reports on Spaceweather.com, observed it streak across our sky. No longer is the term "meteoroid" just the name we give to what a meteorite WAS before it hit our planet, we have actually studied a meteoroid in space, before impact.
On the Bad Astronomy blog, a commenter asked, "What is the distinction between a meteoroid and an asteroid?" The answer is that there is none. An asteroid is just a small, rocky body that orbits the sun. A meteoroid is just the term for a meteorite's state before it impacts earth, there is no size distinction. In other words, for the first time, we have observed a meteoroid.
Very cool stuff. Wished it streaked through our sky here in Tucson, but I made do with watching it on simulated on Celestia. Hopefully, some folks in southern Egypt caught it on tape :)