2014-01-02

Another (almost) announced asteroid impact

A (very) small asteroid was discovered yesterday at Mt. Lemmon observatory - and already seems to be history. According to a Minor Planet Electronic Circular issued today, the rock named 2014 AA has almost certainly crashed into Earth's atmosphere earlier today, Jan. 2. Unlike 2008 TC3, which is to date the only asteroid discovered before it's atmospheric entry, this time calculations were available only after impact, eliminating the chance for any planned observation.

Computer simulations of the possible impact region suggest the asteroid burned up somewhere between Central America and Central Africa - a large stretch. The highest probability is given for the Atlantic just off the coast of West-Africa, making any accidental observations even more unlikely. The impact hence should have taken place in the first few hours of January 2, 2014 (the precise time and location are not yet known).

Monte Carlo Simulation (purple dots) of the possible impact region (source). The corresponding impact times and locations are listed here.
2014 AA discovery image. The asteroid appears as a 19,1mag smear of light (circle). Credit: Catalina Sky Survey, NASA
2014 AA was most probably no larger than 1-4 meters, thus smaller even than 2008 TC3, whose meteoritic remnants were recovered in 2009 in Sudan and are now known as the Almahata Sitta meteorite.

Almahata Sitta fragment. On Feb. 28, 2009, Peter Jenniskens, with help from students and staff of the University of Khartoum, found his first 2008TC3 fragment. Nubian Desert, Sudan. Credit: NASA / SETI / P. Jenniskens

So far, no observations of the 2014 meteor (which must have been very impressive) are known (to me). If 2014 AA indeed burned up over the Atlantic, (weather)satellites may be the only witnesses. In 2008, TC3 was spotted by some distant webcams, two commercial aircraft pilots and a Meteosat weather satellite.

It will be interesting to see if similar images have been obtained for 2014 AA. So far, there is no confirmation 2014 AA indeed collided with Earth. In any case, neither 2014 AA nor 2008 TC3 pose(d) a real threat to Earth and it's inhabitants. They were much too small - smaller even than the object that exploded over Chelyabinsk, Russia, in February last year.

Infrared and visual light composite image from EUMETSAT satellite real-time data of the 2008 TC3 asteroid impact. Credit: EUMETSAT
Update: A simulation of 2014 AA as it approaches Earth:

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