* Astronomy

Asteroid 2008 TC3 Strikes Earth: Predictions and Observations Agree
A spectacular fireball lit up the predawn sky above Northern Sudan on October 7, 2008. This explosion was caused by the atmospheric entry of a small near-Earth asteroid, estimated to be no more than a few meters in diameter. The explosion likely scattered small meteorite fragments across the Nubian desert below. Although such small impact events occur several times per year around the globe, this case was unprecedented because the asteroid was actually discovered the day before it reached the Earth and the impact location and time were for the first time predicted in advance.
At 6:39 UT (UT = GMT) on the morning of October 6, 2008, Richard Kowalski, at the Catalina Sky Survey, discovered this small near-Earth asteroid using the Mt. Lemmon 1.5 meter aperture telescope near Tucson, Arizona. When the discovery observations were reported to the Minor Planet Centre (MPC) in Cambridge Massachusetts, a preliminary orbit computation immediately indicated that the object was headed for an Earth impact within 21 hours. The MPC quickly made the discovery and subsequent "follow-up" observations available to the astronomical community and contacted the NASA/JPL Near-Earth Object Program Office. The MPC also notified NASA Headquarters of the impending impact so that subsequent US government interagency alerts and inter-governmental notifications could begin. By the time this object (now designated as 2008 TC3) entered the Earth's shadow 19 hours after discovery, some 570 astrometric (positional) measurements had been reported from 26 observatories around the world, both professional and amateur.

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