Asteroid impact welcomes in the New Year
Earth saw in the New Year with some celestial fireworks as the first asteroid to be discovered this year, 2014AA, likely impacted the Earth between 7 pm Wednesday and 2 pm Thursday GMT.
Though this is not a rare event, it is only the second object to be detected just prior to striking the Earth. Using the only available observations (from the Catalina Sky Survey at the University of Arizona), independent orbit analyst Bill Gray, from the Minor Planet Center in Cambridge, Massachusetts, and Steve Chesley at the NASA NEO Program Office agree that 2014AA struck Earth's atmosphere somewhere on an arc connecting Central America and East Africa, with the most likely impact site being off the coast of West Africa.
As seen in the orbit plotted above, the Earth was overtaking AA2014, resulting in a very small impact velocity of about 10 km/s. The asteroid is unlikely to have survived atmospheric entry intact given its estimated 2 to 4 meter (6.5 to13 ft) size. However, even with its unusually low velocity, the airburst is still estimated at about a kiloton of released energy at an altitude of about 35 km (22 mi).
2014 AA was comparable in size to 2008 TC3, the only other object discovered just prior to hitting the Earth. While impact is considered a near certainty, infrasound data from nuclear detonation detectors are being searched for evidence of the airblast.